I have two pairs of westones - UM3X that are my 'stay at home' IEMs that are used for jamming, listening both critically and casually, etc. I have a pair of Westone 4R IEMs as well. I've used the UM3X for about three years, nearly four I think. My original pair had the cable short at the earpiece after two and a half years. I called and asked about a possible repair knowing they were full well out of warranty. I was given a RMA# and instructions and off they went. A week or so later I was emailed/called saying they were unrepairable and that they would offer me a (heavily) discounted replacement as they were sorry I'd had the issues. I opted for the 4R set as the replacement and received another's UM3Xs in a gear swap deal.
Now that thats out of the way, I love both. The UM3Xs have a nice midrange. Very very silky for vocals, acoustics, pianos, etc. I love listening with them. The 4Rs are more hi-fi sounding. Crystal clear, tight, I believe a more narrow soundstage. I've used them about 6 months now.
I don't know if I'd ever willingly go back to stage monitors, honestly. I'm a BIG westone fan after 6 years using In ears (sennheiser, Shure, Westone, etc) and can safely say without a doubt I've never heard what I needed any better, with non-ear splitting or headache inducing volumes. I'd HIGHLY recommend anyone try it for four to six weeks to get a grasp on it and adjust to it. It is entirely different, and I believe a step in the right direction for nearly anyone.
As always, YMMV, IMO, etc.