While not "perfect" (whatever that means), the d7000 is indeed a way more "fun" headphone to listen to, which is why I have them on my head a majority of the time. They're great when I watch movies on the computer, TV, a lot of genres of music...sure, the hd800 have soundstage and detail, but they're not exactly what I define as "fun". I think they're great, no doubt, but they're not everyday cans for me.
Seems like the th900 have all that workmanship stuff going on. They sure are pretty...but maybe one day an offer I can't resist will come up and I'll pick up a pair. For now, my d7000/hd800/woody sr225/he-500 combo makes me very happy.
Don't get me wrong, I do like the D7000's as well. And I understand perfectly what you're saying with the D7000 being the more fun and easy-go-along headphone for everyday use. It's a matter of taste and nothing more.
Out of curiosity, what are you using to drive your D7000 and HD800's with? The Yulong A28?
What's the verdict on that one compared to some of the other amps that you have or have had?