I'd say for hard music, go for the Beyer DT770, the DT880 is good for female vocal trance however, but I'd overall say the DT770 is more involving for most trance, techno and hard dance due to its slamming bass and aggressive (but good) sound, these are definetly not laid back. In fact I am listening to trance right now on the DT770's, and I believe I enjoy them for this music better than the DT880.
The bass on a well amped DT770 must be heard to be believed, very visceral, deep and considering how bloated it is, well defined and agile too.
I have heard quite a lot of low - medium priced headphones, and the DT770 beats them all in one way or another, for dance and rock music.
A very exciting sound, and very comfortable to boot...