I know you said your satisfied with what you currently have, but to help some others who haven't been as fortunate so I'll throw my $.02 in. For just lifting, most earbuds shouldn't give you many problems so you could get by with whatever you think sounds good. Probably shouldn't use something too high-end because of all the heavy **** your throwing around, not mention the potential damage from sweat. If you plan on doing much cardio though, your going to need something that twists into place, has an over the ear hook, or simply a head band.
I have a pair of Sennheiser OCX 685i and I love them. The sound is great, but more on that later. As for comfort, after running a couple miles on a treadmill (about 15 minutes) then doing a full hour of lifting I never had to re-push them back into my ears and I never experienced any discomfort at all. I use an armband to hold my ipod, so the controls are great to have in lieu of standing there stretching around trying to skip a song or adjust the volume, and the cable doesn't get in the way because of the supplied clip. Speaking of the cable, it has a rubbery feel and seems pretty durable, some better tension reliefs around the ipod controls couldn't hurt but I haven't had any problems.
Now for the sound. Before using these I used my IE80's for a while (I know this goes against my "don't use expensive earbuds in the gym" comment) and while these aren't quite living up to the sound from those, they sound pretty damn good, especially for a water resistant sport set. I would say the sound is somewhat mid centric with good clear highs and decent bass. Remember, I may be somewhat jaded because of the bass I'm used to from the IE80's, but I definitely would not say these are anemic. They have clear punchy bass, it just doesn't resonate quite like some other more expensive iem's will. Overall I was very impressed with the sound. My experience with some other earbuds in this range has been that bass is bloated and it sounds like mids and highs are being plaid through a plank of wood (I'm talking about you, UE MetroFi 220's).
For anyone considering these, they're about $63 on Amazon right now (for the black) and in my opinion, they're worth every penny. If I had known how these were going to turn out I would have had no problem paying the $80 MSRP. I almost dropped twice as much on a set of Bose, but because of my experience with Sennheiser (and my cynical attitude towards Bose) I decided to give these a try first, and I'm glad I did.
