Thanks for the giving this thread a bump, I had meant to give the forum an update on these headphones as I ended up buying a pair!
Compared to the HD25 I used to run they are a class above, if not two - fantastic headphones, lots of clarity, detail and air. Quite flat too but not boring in anyway, similar in many respects to my Epos ES14 speakers, lots of pace rhythm and timing which is exactly what I wanted. They're not for everyone though, certainly not bass-heads.
They're power hungry monsters though, average listening level is about 12-2 o'clock, not sure how that affects the available headroom (whether it is reduced or not?) but I haven't maxed out the volume either - too loud.
Overall I'm very happy with them paired with the crack, in terms of vfm the two are just astonishing.