Impressed with the sound overall, balanced throughout the frequency range (bass is tight, medium to high frequencies not bad but I still think my Shures are better in the mid to high). That being said, the build is very worrisome - the right shell came apart exposing the tiny speaker and had to be glued. The cord is very flimsy and appears it won't take much of a yank to break the cord. Considering what they cost, I believe a sturdier build could be achieved. There are many China-built IEMs that look to have the same sized housing and can accommodate the same single speaker inside - I bought a pair while in China and for the $7 spent, only the Sunrise's high frequency response was superior.
With XCape I finally have the satisfactory bass with subtle (if any) loss of other qualities. Yes, mids of RE0 and highs of RE-Zero are tad better. But I had to amp them to shine. Unamped, RE0 is slower and RE-Zero is dryer in comparison to Xcape. Add here that I do not use portable amps now and you will get a picture - Xcape is a clear winner to me.
Sound sig: Amped or not, Xcape is not inferior to REs. It rather suggests alternative sound signature with more body and fun at the expense of some very subtle details. This is what I prefer, so Xcape is better all-rounder to me. And it keeps this advantage either it is amped or not. When amped, Xcape also improves on SQ, like REs do, and keeps a parity.
Comfort: Xcape is a bit better in terms of fit to me. I prefer over-the-ear style with all of these three IEMs. Due to the bended strain reliefs and differently shaped shells, Xcape is more comfortable to me.
Are REs obsolete now? No. The final choice depends on your source and genres preference. If you prefer acoustic music and use amps, then I heartidly recommend RE0. For unamped listening of electronic music or movies, some may prefer RE-Zero. If you are unamped and listen to almost everything, like me - choose Xcape then. If you already have any of REs and it suits your needs well - keep it, the differences are subtle, all three IEMs mentioned here are pretty similar. If you do not like any of REs much, keep away from Xcape as well - it doesn't offer night-and-day difference. Basically, I may describe Xcape as a blend of RE0 warmth and RE-Zero sensitivity.
Drawbacks: I much prefer REs visual style, especially RE-Zero gunmetal color. Xcape looks cheap in comparison (though it is cheaper indeed). Included tips choice are also better with REs, though Xcape repays this by the included case.