Good review! Out of curiosity, have you tried the 64 Audio A4s? Supposedly, they're the custom equivalent of the U4s, but with slightly less treble energy.
Headphone Reviews and Discussion - Head-Fi.org
Intralaust
Trance_Gott
No sorry I never heard the A4s.
vikinguy
They're my favorite of the 64 sets I've owned (u12t, u6t, Nio, and duo and I really liked all of those. Here's the kicker. Precog sold his u12t and bought u4s.
Yes, you heard that right. This set is amazing.
Yes, you heard that right. This set is amazing.
DJ Core
Excellent review. May snatch one up down the road.
MJSable
Looking forward to trying these. Thanks for the review. 
FYJX
had a good session at NAMM with @Sebastien Chiu listening to these. Honestly a really great product, and they sound pretty great.
el-jorge
Great review. I have a trio. Would this be an upgrade?
Trance_Gott
Trio has fuller mids but U4s better highs. Bass equal. Both awesome IEMs for metal. I like the little bit recessed mids as complementary to my Blanc better. But when you like your Trio I would say U4s is a side grade not upgrade.
vikinguy
A side grade at $1099!
64 audio is really doing a wonderful job of making incredible sets and charging less. Amen
64 audio is really doing a wonderful job of making incredible sets and charging less. Amen
