Because the 990 is based on the P-965 platform, there should be very little difference sonically (aside from possible benefits of having more control over your bass management, which with those big M80ti's might be a fun thing to experiment with a bit). I personally think the 990's menus are easier to navigate. Sherwood does include the auto-EQ, and Outlaw has considered it but reportedly were disappointed in the solution. In light of the recent arrival of the Velodyne SMS-1 in Outlaw's online store, I suspect that Outlaw's either written off the Cirrus auto-EQ or are holding out for significant improvements (which may not be possible with the existing hardware). Audyssey would be a better solution, but if Sherwood did it with an on-board fix it is very likely that the fix could be carried over to the 990 platform. On the other hand. the cost of doing Audyssey after the fact would potentially come close to the price of an SMS-1, which is Outlaw's current recommendation for EQ (and a very effective solution, at that). Since you already have an Oppo, you are potentially in a position to need the DVI switching in the near future - an HD cable/satellite receiver, PS3, or HD disc player (Blu-ray or HD-DVD) could tempt you toward having a second DVI/HDMI source.

The Sherwood has been very well received ever since it was introduced, but in my opinion the 990 offers some additional features that are hard to argue with.