The thing that's great about the DT770's for recording is the isolation -- there are few headphones that isolate better. You can be right in front of the microphone, with the compressor set so high that you can hear eyelids blink*, and monitor fairly loudly without feedback.
And yes, very comfortable.
The DT880's are like the DT770's without the ...erm... hyped bass signature. I suspect rockers at Guitar Center like the DT770's because of that bass hump.
EDIT: This last is from memory, and I don't know which version of both I heard. I own the 250 and 600 pre-pro/home split (which effectively makes them pro, I think) of the DT770's, but have only heard the DT880's in meet environments, but I don't remember which DT770's were at the meet.
*Yes, I've done this, really -- it's a surprisingly wet and intimate sound. And a little bit TMI.