Well, you'll also lose the 1400's amplification, unless you're already using the 1400 as a pre/pro with separate amplification.

What will you gain? Pro Logic IIx, 7.1 analog input instead of 5.1, digital bass management on the 7.1 analog input, more flexible bass management, and of course the expanded video switching that you've already mentioned (an extra component input as well as 2 input DVI switching). I'm not sure how the AV sync works on the 1400 (if it is global or assigned to each input), but the 990's is specific to each individual input. I liked the Yamaha receiver that I had a few years ago, but I would expect the 990 would offer one difficult-to-quantify improvement: sound. The 990 is a really nice sounding piece of equipment, much like the P-965 (which has garnered widespread praise since its release) that the 990 is based on. Whether that improvement is enough to sway you to spend the cash for the upgrade is something of a personal choice, but there is a 30-day return policy - if you are on the fence and are OK with parting with the shipping cost, you can give it a try and return it within 30 days if the improvements aren't enough to win you over.

Plus you have Outlaw's support staff to help out, and of course the folks around here to bounce questions off of as well...