Disclaimer:
I purchased the FH5 for personal use with my own money. I didn't participate in the review tour. I'm not affiliated with Fiio in any way. In this review I'll be comparing the FH5 with the Fiio F9Pro and iBasso IT03 (my current benchmark for a U-shaped mid-fi IEM), both of which I've owned and used extensively. My main source is a Hiby R3 and I've been usng them on and off for ~60 hours now.

What I look for in a IEM:
I don't consider myself a really discerning listener. In many cases I can't tell between FLAC and 320 MP3, hence I rarely venture beyond the mid-fi market - just makes little financial sense for me.
My general sound preference is a nice balance between fun and detail - a well extended and mild U-shape, where subbass is a little elevated vs midbass, and the treble's highest peak is at 10kHz. I have small ears, between S and M tip size, depending on insertion depth. To me comfort and design are just as important as sound. My music library includes includes a mix of FLAC and MP3 of classical, jazz, breakbeat, trance, techno, hiphop, pop, hard rock and heavy metal. For a full list of my IEM inventory check my profile.

Some pics:


Non-sound:
They are way smaller in real life than the photos would have you believe - as small as the F9Pro, just a different shape. Fit and comfort are as close as you can get to perfect with a universal-fit shell, even with my small ears - slightly better than my F9Pros and much better than the IT03, whose inserion is so deep that the nozzle edges press against my ear canals. The FH5 shells barely stick out of the ear for a very low profile fit. This is partly because of the shallow insertion depth but I have no problems using single flange tips. I actually welcome the shallow insertion depth as I can experiment with a wider variety of tips like double flanges and foams without the shells sticking out of my ears too much - something I rarely achieve with my other IEMs. Another huge pro is that unlike many mid-fi IEMs the nozzles are ridged so the tip fit is nice and secure.

Speaking of the nozzles the FH5s have 3 separate sound ports for better separation but I'm not convinced the mesh in front of them was a good idea. Sure it protects them from dirt but in my opinion somewhat defeats the purpose of having separate ports, which is why some owners elect to remove it.

Isolation is very good for a vented IEM. For me it's much better than the F9Pro's and on par with the IT03's, which is my benchmark for good open IEM isolation.

The cable is simply gorgeous and doesn't tangle easily. It's little heavy for working out but serviceable. It does retain some memory when wrapped for a while but it's not hard to straighten back to shape. The earhooks are pre-formed tubes, not wire, so you have less freedom in shaping them. I don't mind it but I would've liked the tubes a couple of cm shorter. The MMCX connectors are very tight and secure and I love that they are angled and not straight. It takes a bit of effort to rotate them, unlike with my F9Pro, where the right one is really loose. I just hope the cable wont harden or turn green like most transparent sheathing ones do. It's interesting Fiio didn't choose to include a mic or a balanced cable like they did with the F9Pro but I don't mind at all - don't need either of them and this probably kept the price below $300.

Tip selection is identical to the F9Pro's, with sufficient number of sound enhancing tips. I would've appreciated the inclusion of very wide bore tips for those who want their treble a little more enhanced. My wide-bore shallow-fit Sennheiser tips make the sound signature slightly closer to the F9Pro's. The silicone on Fiio's tips is also a little hard and slippery for my taste. I much prefer using Sony Hybrids when it comes to comfort.

The included case is a very welcome accessory - same as what's included in the F9Pro but clear. Fits the FH5 perfectly and it's much better than what you get from most other brands in this price range.

One thing that I personally dislike about the FH5's design is the golden bezel around the faceplates, and the overall glossiness of the finish. They're sexy when they sit on the table but they get too bling-y for me when in the ear. Almost look like cheap jewelry. I much prefer the F9Pro's subtler matte metallic finish. Hopefully in the future we'll see more color options.

Driving the FH5 is a piece of cake, even with very low power sources. Although their impedance is more than 2x that of the IT03's 8 Ohms, they are the most sensitive IEM I've owned. The 19-Ohm impedance however is not ideal for use with most lower end sources. I get a completely black background from my Hiby R3 on low gain, and directly plugged into my Alienware laptop (Realtek audio chip), but I hear some hiss with my BlueAnt Ribbon bluetooth dongle and my Dell docking station.

Sound:
In the sound department my impressions are in line with Brooko's measurements. The FH5 is not a U/V-shaped IEM. It's more laid back than your typical V-shape, but not flat or overly warm. If you're into measurement graphs, like I am, you'll notice it's very close to the updated IEM Harman curve but its treble doesn't roll off steeply after 2 kHz - something I wholeheartedly approve of. I would define their tuning as "smooth, musical and detailed" and it works well with the wide variety of genres I listen to.

Starting with the sub bass, the rumble is definitely there when called for (on par with the IT03's) and it has substantial extension all the way down to 10 Hz. Midbass drops slightly but is still present and textured, however I find both the F9Pro's and IT03's midbass a little better textured. Because of the elevated mids, the low frequencies often take the back seat, especially on busier tracks like heavy metal. They are back in full strength when playing hip-hop or EDM.

Mids are much more forward than the IT03's, but even though I generally appreciate slightly recessed mids, I wouldn't call the FH5's mids fatiguing, at least not at low-to-moderate listening levels. Regardless, this mid-forwardness makes the FH5 sound very musical and immersive - the vocals and instruments are articulate and present and don't get lost inbetween the low and high frequencies like they sometimes do with U-shaped IEMs.

Highs are where I understandably have my doubts. They aren't too rolled off or at all grainy. They are relatively smooth and have presence all the way up to 17kHz (to my hearing). There are three notable peaks - 7kHz, 12.5kHz, and 16kHz - and each peak is around 3dB lower than the previous.
Unlike some laid back headphones I've tried, "S" sounds don't sound as "SH" and micro-detail and sparkle is there, however cymbal crashes and hihats lack the emphasized sparkle U/V-shaped headphones typically have. This is particularly apparent in tracks where the highs are already recessed. Ideally I would've liked to see another 3-5dB on the second peak, which would increase the sparkle without reaching the piercing levels of the F9Pro. EQing fixes that easily but I prefer not to use EQ if I can.
The upside is that the highs sound more natural than the sometimes metallic highs of a U-shape, and are much more non-fatiguing for extended listening sessions.

In a nutshell:
Design form and function: 8/10 - gorgeous, comfortable, but a bit bling-y, nozzle mesh questionable
Build quality: 10/10 - top notch; well executed connectors
Comfort and seal: 8/10 - great comfort even for small ears; good isolation
Cable: 9/10 - beautiful, comfortable, hard to tangle, a little heavy; earhooks could be better
Accessories: 8/10 - missing wider bore and softer silicone tips; great carrying case
Sound: 9/10 - Smooth, musical, fun, and detailed
Value: 10/10 - Would I recommend them - absolutely, unless you're a treble junkie or a basshead and don't like EQ
Are they an upgrade over the F9Pro or IT03: Depends. They have a different sound signature. That being said, even if I lean towards U-shaped sound I would still take the FH5 over either the F9Pro or the IT03. The FH5 just get so much right that I'm willing to overlook their small flaws.

**Updated 10/27/15 - 10 months of ownership**
 
Disclaimer:
I purchased the W30 for myself and am in no way affiliated with Westone.
 
Background details:
I've spent a while searching for a comfortable slightly warm IEM that isolated noise well, had detachable cables and most importantly - offered high resolution with a touch of rumbling bass. So far my search had led me to the world of hybrids but I found the most popular models in the audiophile community had either problems in the treble and/or weren't too comfortable to wear over an hour or so. Well my search seems to have come to an end...for the time being at least.
 
I won't spend too much time on the packaging and photos. There are plenty of photos and videos out there, which you've probably already seen. Jumping straight to the meat of it.
 
Design, build quality and fit:
Happy to report Westone have stayed true to their funciton over form design philosophy. The design is very inconspicuous and it seems every aspect of it is focused on comfort - no rough edges and nozzles are slim like Shure's models. The only exception is the swappable faceplates, which IMO add questionable value. It's nice to have a blue left channel and red right but they kept cracking right below the screw. Westone sent me replacement ones but it keeps happening for some reason. 
 
The fit is the most comfortable I've tried to date and I have literally no complaints in this regard. I can wear them for hours and there is no way they can fall off my ears. The epic twisted cable seems flexible, sturdy but also thin and inobtrusive. Unfortunately it hardened pretty quickly in the parts that touched my face and started tearing near the housing tension reliefs. Westone replaced it but it happened again. I bought the earhook epic cable for the UM Pro series and it has worked well for me for over 6 months now. The iPhone G2 cable is pretty useless to me as it's too springy to stay over my ears and I don't use Apple devices.
 
The standard Westone tips are new to me and I am extremely pleased with them. Even the short medium silicones feel much better than what I am used to. The long ones seal easier but they are a bit too long for my canals causing the housings to stick out a little. My only criticism here, and mind you I'm nitpicking at this point, is that the housings could feel a bit more premium for a $400 UFIEM. I would even be happy with a clear plastic option. Also I was a big fan of Westone previous generation's 1, 2, 3, 4 stylized logos. Not loving the W logo as much.
 
Ok now to the really important stuff - sound. My listening is done with either the medium short (black) star tips or medium Shure olives with removed filters. As you will read below, the other tips change the signature for the worse so I avoid using them. My source is mainly my Fiio X1 (no amp) and sometimes my LG G3 (for streaming services).
 
General Signature:
I would define the signature as mildly v-shaped.
 
Lows:
The first time I put them on I was expecting there was no way the bass could come close to a hybrid. Boy was I wrong. They were a bit underwhelming the first time I put them on but an hour in I constantly found myself decreasing the bass bump on the EQ I had initially implemented. Goldenears' measurements show these have the most linear bass out of all Westone models and I agree completely. There is no noticeable midbass bump and the bass is typically quick for BA. No bleed into the mids. I think only bassheads can't be happy with the bass.
 
Mids:
Although mids are slightly recessed, both male and female vocals sound great - not nasal and not distant, very articulate. The detail is great and I can hear details I haven't heard before. In the first time in my life I'm actually looking forward to songs with lyrics.
 
Highs:
All my other BA IEMs have had some issue with the highs - too recessed or too hot. Sibilance is a big issue for me as I love the treble energy and sparkle but I am very sensitive to sibilance. Happy to report listening to sibilance-prone genres like heavy metal and drum&bass even at high volumes, I didn't notice any sibilance whatsoever. Furthermore, this is my first IEM where there are no glaring peaks or dips in the treble. At the same time the highs are very detailed, sparkly and, as with the mids, I actually hear details that I haven't heard before.
 
Resolution and soundstage:
Hands down these are the most smooth and detailed IEMs I've ever tried. I have a few tracks that have always sounded distorted at some spots with any of my other IEMs, but the W30 made even them into masterpieces. The soundstage is pretty track-dependent IMO. I have some songs that felt really airy while others felt like the band was right next to my ear.
 
A note on tips:
After spending a while tip rolling, I found that the short star tips and Shure olives with removed filters give me the best sound and fit. None of the long star tips worked for me as they created a mild sibilance and a midbass bump. Don't like the westone foams at all - they lose seal easily and create the same sibilance and midbass bump I see with the long star tips.
 
Conclusion:
The W30 are still my favorite IEM to date. Even the UM Pro 50 couldn't win me over. They have great bass slam, smooth and detailed mids and highs, a closed IEM noise isolation and the ultimate fit and comfort for a universal fit IEM. They work great with every music genre I throw at them from jazz and classical to bass-demanding EDM and hiphop. Really happy with my purchase and I hope they last me a long time. Highly recommend to anyone that can afford them, except for die-hard bassheads or ppl who are looking for flat sound signature.
 
Comparisons:
UM Pro 50 - Treble is more laid back than W30. Midbass and mids are more present. Sound is warmer and more natural. W30 is brighter and crisper.
Dunu DN1000 - Treble gets too hot at high volumes and is not as detailed. Bass is slower but more in quantity. Subbass is more elevated. Mids are slightly more recessed.
Fidue A83 - Treble is more laid back than W30. It's drier and doesn't have the W30's sparkle. Mids are more present. Bass is similar.
JVC FXT90 - Very similar signature. Treble is slightly more recessed. Mids are slighly more elevated. Subbass rolls off a bit, whereas W30's extends all the way to 20Hz.
VSonic VSD1 - More pronounced v shape than W30. Highs have similar energy but get sibilant at high volumes. Not as detailed and as sparkly as the W30. Bass is more in quantity and a bit slower. 

I purchased the T10i for myself and spent about 50hrs listening to electronic music, hard rock, heavy metal, jazz and classical while sitting, sleeping or working out.
 
This is an emotional review for me as I was really excited to see such a well built and ergonomically designed IEM that didn't skimp on the lows but still (according to reviews) managed to maintain high resolution and clarity. I won't spend much time on the packaging and accessories. There are plenty of reviews and photos out there already covering these. Will focus on what matters the most to me - design, build quality, comfort and sound quality.
 
Design and build quality:
These things are gorgeous and seem bulletproof. They should be put in a museum for people to marvel at. For me $195 out of the $200 I paid for them are worth that amazing design and build. It's obvious a lot of thought has been put in the design not only from a "form" aspect but also from a "function" point of view. I love their form factor and the low profile they have when they sit in the ears.The patent pending earguides are a great idea but they are are bit too long and heavy so as a result their lower part wiggles around behind your ears when you move your head. Also when you want to store the IEMs you will either have to change their shape every time or use quite a big container. Moving down, the cable is phenomenal. It's soft and thick and I doubt there would be any microphonics even if these could be worn cable down. This is my first pair of IEMs where I don't worry the cable will snap every time I tug it too roughly and where I don't care the cables aren't detachable. The remote is nice and easy to use but it's a letdown that there is no Android option for it.The Y-split and the plug are both great, stainless steel and I love the metal spiral cable relief on the plug.
 
Comfort:
As one can expect they are above average in this aspect. The housings are small enough to fit in smaller years and the nozzles aren't too wide. Achieving proper seal was a bit hard for me for some reason. I resorted to my stock Dunu reinforced eartips for a better fit. Compared to my Vsonic VSD1's swiveling nozzles, the T10i's were a bit too angled for me. I would prefer ~60 degrees vs. the ~85degrees of the T10i. Still the T10i's are the most comfortable IEM's I've tried to date after only the Westone W30 and even sleeping with them on was a breeze.
 
Sound:
This is where it goes downhill for me...
I love plentiful bass. I even thought of myself to be borderline basshead. When I got them I expected very warm sound, lots of bass and not-that-detailed mids and highs. Because of the reviews I've read, when I opened the box I immediately switched to the "treble" filters even before playing anything. To my surprise the lows were still just annihilating any other part of the spectrum apart from some highs between 8 and 10kHz. Just out of curiosity I tried the "reference" filter and even those little highs disappeared. So for the purpose of this review I'm not gonna even bother with the "bass" and "reference" filters.
 
Lows - If the T10i aren't a basshead IEM, I don't know what is. The bass extension is great. There is a powerful subbass rumble that you can feel all the way in your mouth, which I love. The midbass is too strong for me though. I had to eq it down by 3-4dB. The speed is not great either - all my other IEM's fared better in this regard. On a positive note, the bass doesn't bleed too much into the mids and didn't cause any notable distortions
 
Mids - So laid back that they are virtually non-existent. Any vocals seem quiet and distant and in many cases I was struggling to hear them over the powerful bass. Honestly I'm not a huge fan of mid-forward IEMs but on these even I had to eq up the mids by 3-4dB just to bring them to acceptable levels. Even so they still sound muddy and unrefined. Great for dance and hiphop but a nightmare for rock, classical etc.
 
Highs - Treble is a hit or miss. There is some treble sparkle but still leaves more to be desired. For me there is a very significant dip in 6500Hz followed by a mild peak in 9kHz. With proper eq-ing the treble can actually become quite pleasant. The detail is still not quite on par with some of my other dynamic IEMs like the JVC FXT90 or even the bassy VSonic VSD1.
 
Soundstage - I didn't find the soundstage to be particularly wide but with so much bass it's really hard for me to judge.
 
Noise isolation - I have no idea why pretty much every review out there says the T10i isolate above average. For me they had he worse isolation out of any IEM I've ever owned. I could carry a normal conversation with the music off.
 
A note on tips - I spent several hours tip rolling both for fit and sound purposes. Interestingly I didn't notice any significant effect on the sound from changing tips.Wider bore tips like the Auvio and Dunu's reinforced stocks did improve the treble a little. The Sony hybrids and Comply foams improved comfort a bit vs the T10 stocks.
 
Conclusion:
The reason I mentioned this review was very emotional for me was because I think there is a lot of wasted potential here and that drives me bananas. I think such an extraordinarily well made product should come with a sound quality to match. If the "reference" filters leaned towards a flatter signature, the other two would have really been valuable, but in this case the T10i sound really really consumer-oriented, belonging right next to Beats in the Apple store. I really wanted to love the T10 but I did end up returning them. I really hope RHA makes a revision with a more refined sound ,maybe even a hybrid. I would gladly pay $100 extra for a dual BA in addition to the dynamic driver. Now that would be the ultimate universal fit IEM for me...

Update after about 3 months with the DN1K.
 
Design, build quality and fit:
The housings feel very solidly built, although some ppl have reported the glossy finish peeling off. Cans are a bit heavy but no problem staying in my ears, even without the spacers. Wearing them cable down can become fatiguing on the ear canal after a couple of hours, but cable up with the earguides is a breeze. Unfortunately, they are not great for sleeping with. The nozzles are the widest I've seen on an IEM (the balanced armatures are housed there) so they are definitely not for ppl with small ear canals. Cable is thin and there are a lot of cases of the cables stiffening where they touch your skin (including mine). Among other things this really increases microphonics, even when worn cable up. I had to return my set to Dunu for a replacement. The Y-split is metal and looks high-end but the side that has the serial number has rubbed off just after 2 months of use. One more thing I find annoying is the rubber wrap that I can't hide anywhere so it dangles around when I walk.I know a lot of ppl love it but I just don't find it practical, especially with that sexy storage box you get with them.
 
Tips:
The clear single flanges (no spacers) give me the best fit and seal out of the silicone tips, while offering great sound at lower volumes. The reinforced stock silicones get good sound at low volumes but fit isn't as great as the clear ones. But damn they look cool
The foams are way better than the ones I got with my VSonic VS1D - almost as good as Complys. Either stock and Comply foams work wonders with the sound at both high and low volumes. I use the Complys for the ultimate sound, comfort and sound isolation, but obviously this can become expensive.
The stock bi-flanges are decent but same as with the MEElec bi-flanges, I get a midbass bump and harsher highs. Tried my Sennheiser single silicones on but they slide off way too easily from the nozzles. My JVC silicones work well but I get the same sound as the reinforced stocks.
 
Sound:
Definitely v-shaped. Impressed by the DN-1000's ability to keep their cool at high volumes with no distortion whatsoever. None of my other IEMs can do that quite as well.
 
Bass is very abundant and has a nice sub  bass rumble. A bit lazier than on my JVC FXT90 but much more in quantity. No noticeable bleed into the mids and quite detailed.
 
Mids are much more recessed than on the FXT90s, which works well for electronic but might not be perfect for other genres. I think that the Fidue A83 fare better, especially with guitars and vocals.
 
Highs are bright and on the verge of sibilant. At low to mid volumes it's perfect but in noisy environments where you need high volume, the highs can become fatiguing without EQing them down. Foamies definitely help reduce the sibilance but are not as effective as eq. The detail is great though and you can feel every subtle texture of the hihats and cybal crashes.
 
Soundstage is decent and the resolution is phenomenal for $200 IEMs. 
 
A note on the spacers:
I seem to be one of the few that doesn't notice any difference in the sound switching between spacers. The only thing I noticed is that if I use foamies with the spacers the highs get attenuated too much.
 
Earguides:
I was initially very disappointed with the earguides but after I got used to them I don't take them off at all. Nowadays I can't even feel them on my ears. They have a very smart design that doesn't let the cable get out easily (like the VSonic ones do) and they are quite small so not a huge pain to store the Dunus in the relatively small box provided. 
 
Overall:
So far the Dunu DN1000 is one of my favorite IEMs as far as sound quality and sound signature. They are a real bargain, even for the original MSRP of $210. I wish they had a more ergonomic shape and I really really wish Dunu had put more effort into the cable - braided, detachable or both...