One feature that the Denons have that I've missed since going to a 990/770 is the ability to use A, B or A&B side surrounds. I always liked using a set of direct reflecting surrounds to the rear of the room for mucic, particularly classical where the surround is primarily rear wall reflection. I have an old Rat Shack speaker selector around someplace that would let me duplicate this feature with the 990 but I've never bothered to set it up, so obviously not having this feature isn't a big deal.
Another neat feature is the ability to select digital, analog, or 5/7.1 direct input without changing video sources. This gave a lot more versitility in hook-up. My biggest concern with the 990 has always been the number of inputs, particularly video inputs, and having to use 2 to hook up a single DVD player ( one for digital inputs, one for 5.1 direct for DVD-As and SACDs)just aggravates the situation.
The 990/770 is far superior to the Denon sonically, but the Denon showed a lot of thouhgt in it's feature set and certainly has a more useful remote.