Thanks for the great comparison, I've been waiting for one for a while. As a Denon fan myself, I'm a bit worried about the HD800 bass impact, but no use speculating. I have the HD800's pre-ordered so we'll see soon enough.
+1 on that lol.
P.S. If you are listening at volumes loud enough for sound to leak OUT of a closed pair of headphones (such as the D5000s) so that someone else in the same room sitting 10 feet away can hear it, then you will not have to worry about headphone isolation for long at all, as you will be deaf soon enough if you continue listening at those volume levels. Trust me on this one, and please heed my warning.