I think I'd rather have a warmer set than a dark one.
Here's a good example of a song that has most of the elements I want in a good pair of headphones: http://www.youtube.com/watch?v=gs8I0ZqvNGk
Pretty warm tone to it, good acoustics, good bass, but not necessary for it to be "punchy", ability to separate the sounds of a complex song, large soundscape, etc... Also usually the stuff I listen to isn't focused on vocals so they're not a huge deal.
From what I've been reading the HE-400's seem to be perfect for this, but dammit I can't find anywhere I can try it out so far.
EDIT: Sorry, quoted instead of edited.