I'm shopping for a similarly featured/sized player. I've spent quite a bit of time with my girlfriend's nano this week, and I'm really surprised how much I dislike it. My biggest annoyance is the bass... it seems like there's a whole octave missing, it just isn't there. Even with over bassy cans and buds like the MD33, EX71, EX81, and K26P It refuses to reach deep enough for my tastes. I don't consider myself a Basshead, but I do atleast want to hear all of my music. The rest of the spectrum sounds pretty neutral, with good resolution too.
Little things bug me too, there is background hiss at even moderate volume levels. I would describe changing volume as "dirty" - each transition is harsh. Same goes for pause/play, and inter-track gaps. This is all nit-picky stuff, but it adds up.
On the plus side, the interface is decent, and the size is nice. While my impressions aren't based on UM2 considerations, I think they would apply regardless of the cans you use.
I haven't yet tried it with Rockbox (next week) - I would be pleasantly surprised if that filled in the low end, but I somehow doubt it.
I was about to order a Nano a few weeks ago, but I'm glad I heard one before buying. If you can do the same, I highly recommend it as i was truly surprised how wrong the Nano is for me.
