After over 10 years of listening, I'm trying to move away from IEM's for portable use. After lots of research, I narrowed my decision to the Senn Momentum and the DT1350, ultimately going with the DT1350. So far I have mixed feeling about them but that's probably because I've been so used to my Westone 3's. Using them with my Cowon J3, I'm finding I really need to crank up the volume. Where I used to listen at a volume of 18 -20, I now need to go up to 30 -34, and even then I feel like it needs more oomph. I want to see how they fare with an amp so I'll have to dig out my Xin Supermini.
I'm also finding them to have a bit more bass than I prefer on certain tracks so I'll have to tweak the equalizer settings on the J3. Another thing I've noticed is that vocals aren't quite as forward as I'm used to, but overall I am impressed with the sound quality. Comfort hasn't been an issue either. If I have one major gripe, it's that I think I look like a real dork wearing these things, to the point where I'm self-conscious about it in public. Before I switched to IEM's, portable headphones were a lot smaller and less obtrusive.
Provided my ears can fit comfortably in the cups, I'm still probably going to get the Senn Momentums for comparison purposes. I know some people feel they're several steps below the DT1350 but based on many of the reviews I read, they may be more of what I'm looking for.