I've owned the UM3X for months, and I don't quite like it. However, I do believe I'm hearing these wrong (check my post history, I mentioned a few times about not liking the UM3X). I bought a 2nd hand UM3X and these don't come with its default tips. The one that comes with the seller sounds best but is sibilant (silicone, single flange with quite a distance from the IEM opening to the ear). I've tried the Sony Hybrids as well (and some masking tape to make it fit). They make the sound muddy, killed the sound stage, although it's much easier to get isolation and got rid of the sibilance. It's probably because the IEM opening is closer to the ear with the hybrids.
Maybe I should try mod the Sony tips further, so that the distance between the IEM opening to the ear is further. Going to try that out and find out. EDIT: Oh yeah, it works. Of course, the sibilance is back but I can live with that for now.
That's pretty much my experience. Any recommendations for a non-foam tip? Let's just say Sony Hybrid teal tips (size M) fits best on me.