Guys, I wouldn't let me put you off buying a D800.
I bought the D800 on a whim. There were such good write ups and reviews I thought it would be worth checking out. It was, but running both amps side by side at home and on gigs left me slightly preferring the more "vintage" flavour of the TH500. I don't have any negative thoughts about the D800 at all. The TH500 was an instant love affair and the honeymoon period lasted more than 4 years. I use it at home and I still gig it on occasion.
Again, I bought the AG700 to check it out. I had very little idea what it sounded like before and I was pleasantly surprised when I heard it. It's like the TH500, but cleaner, slightly less "vintage", more punch, breadth of tone and more "oomph". I seem to be preferring my P bass through the TH500 and the Jazz through the AG700.
The other feature that really interested my was the AG700 can run at 2.67 ohms. I've use 3 8 ohm cabs in the past (and might again) and I'm currently running 4 ohm and 8 ohm cabs together and separately.
Both the TH500 and AG700 were lucky accidents. They appealed to me instantly. The D800 is equally good but just didn't hit the spot in the same way.