Not me. While the camera on the 5t is crap, the rest of the phone is top notch. Anyways, I'm not really a frequent upgrader and I expect to be using my 5t for a while yet.
Honestly, I would seriously question that assumption. I went from a nexus 5x to this and am having pretty much no issues adjusting. It's only about 3mm wider. The height is another matter but that is much less important I'm finding. YMMV.
I'm keeping mine on until I'm sure I'm not returning it...... Which should be soon as I'm really liking this phone! Not a big fan of screen protectors either.
It's not on the official list but it's quite possible the list is not entirely up to date:
Device Compatibility | Samsung Gear S2 - The Official Samsung Galaxy Site