Seeing the prices of the 990 dropping, I'm somewhat interested (probably will wait for the successor though) in picking up a 990 and an amp as an upgrade over my 1070. It's quite a handsome piece of equipment - but it's girth is something I really notice in the pictures. What about the insides of it makes it so large heightwise?

RedSIinPA,
More like the space required for the back panel. Take out the balanced connectors and you could loose some height (for example).
Later.....

The 990 uses the same case as a receiver (Sherwood R-965?). So, all that room was used up by amplifiers in the Sherwood. One of the advantages of a large case is it is easier to do hookups on the back and all the extra room might also explain why the 990 has balanced outputs.

Just take a look at the back panel. They needed the height to get all those connectors in place. In fact I wish there was a little more room back there. Once you get 4 or 5 digital sources plus 3 DVI cables, all the XLR cables to the amp and then add in the analog cables and you are pretty tight back there. I am running a 5.1 surround system and I have nearly 30 cables connected to the back of my system! All in all I think they did a pretty good job of using the available real estate.

My biggest wish would be for them to give more room around the 7.1 analog inputs. When you are using decent RC cables such as the Outlaw Cables the connectors are nearly touching each other, which makes it very difficult to make all those connections. Especially when you have hands like "The Thing" from Fantastic Four!

Moving from DVI to HDMI should reduce the size needed a bit, methinks.

I also hope they move away from USB and go with an ethernet port on the future product.

But mostly I hope they work out as many bugs as they can before releasing it to the public.

I'd rather have a product with fewer "nice-to-haves" that is more solid and less quirky than the 990 is now.

Specifically, make sure it doesn't make popping noises when switching surround modes, or doing anything really as this is annoying and potentially damaging to speakers...and quicken the amount of time it takes for the player to figure out what kind of audio stream it's working with.

AvFan's right on target - the chassis used for the Model 990 was developed by Etronics originally as a receiver with seven channels of amplification (and something like 120 watts per channel), so there was originally a lot of additional hardware on the left and right sides of the chassis. Outlaw used that real estate for the balanced outputs and DVI switching.
The 990's replacement would only be likely to use the same height chassis if Outlaw were to use an Etronics platform that also retained that chassis (I've read that Sherwood will have a receiver that retains that same cabinet). Moving from DVI to HDMI will not help any - the cabinet dimensions will be dictated by other factors. Is it being developed solely by Outlaw and Eastech, as the 1050, 950, and 1070/970 were? Is it being based on a platform developed by someone else, as with the 990 and the Etronics/Sherwood R-965/P-965? If it's the latter, was the platform developed as a receiver first? That is the sort of stuff that will determine the height of the cabinet.
Compared to other products I've used, the 990's speed is pretty respectable here (fast enough that it doesn't generate snide remarks from my wife, who I consider an excellent test subject for evaluating signal acquisition time). On the other hand, part of the October announcement that mentioned waiting on a final implementation from Cirrus for the 49700 related to getting really fast signal acquisition times for the new audio formats, so we may see even faster acquisition times than the 990 exhibits in the next generation. (Rampant speculation mode off, as it's time to eat some lunch before my next meeting...)

My RDC-7.1 has no such issues when locking on to signal type.

If I remember correctly, the 990 had about a half second lag time when a source was first turned on.

I would agree that the 990's acquisition time is around half a second, but that compares to a second or even a couple seconds for many other surround receivers or processors. The Model 950 averaged closer to one and a half seconds, and Emotiva's LMC-1 apparently takes around two or three seconds in many cases.

Heh, guess I'm spoiled then.

The thing I always wonder is why it is so deep. Height I can see, because of the connections on the back, but man, it's deep. Guess it's just because of the shared platform aspect, which probably in turn relates to better prices. All speculation of course, what do I know.