The soundstage is wider than the HD650, but less deep, I agree about the imaging, definition and clarity is above average. Bass is less tight than the TH-900 (higher distortion), I think you mean to say it has a more balanced frequency response so that it the bass doesn't sound as intrusive/overbearing, which I kind of agree with, it varies on the material as on some songs the THX00 bass dominates the soundscape much more than the TH900s does.
Nice review.

Fun to read, I also joined the boat.
Actually I am selling my HD800. Find them boring when I have listened to my LZ-A2's.
Appeares I like the fun sound more, so hopefully these TH-Z00's do the job.