Like I said, I sold my HD700 so I can't directly compare, but from memory, I have to say the way I'm amping my HD800, it has a very similar tonality and sound signature as the HD700 with only superior technicalities across the board. Imagine the HD700 with a wider soundstage, cleaner and more texture bass with body and tactility, better detailing, and most importantly refinement and lack of grain. The biggest flaw I found with the HD700 was its grain and refinement not on the level of some other headphones I have like HE-500, HD800, and T90. I remember distinctly A/Bing HD700 and T90 and it was clear the HD700 was not as fine sounding. But imagine a headphone that had the HD700 sound signature, but without the problems of refinement, and having the HD800 superior technicalities. That's pretty much what I am listening to right now and enjoying very much.
This brings up a good question for those that have or had at one point both the HD700 and HD800: Technicalities aside, do you prefer the sound signature of the HD700 or HD800 more?