Yah I would definitely go the separates route, better all around flexibility and choice for you down the road. Not to mention, you probly will get more power/headroom out of the Ultra 550 than the integrated?
Personally I'm not a huge electronics guy, power is power for the most part to me. I can't see myself ponying up 8K for a preamp/power, I don't think my entire custom 5.1 Salk setup cost 8K. When I go and listen to some of these big name electronics makers, I don't really hear that much a difference between them, and while they sound better than some of the more value brands, they aren't that much better nor would the difference be noticeable to me unless I was really paying attention (which I'm normally doing something while listening). Or, to take advantage of them to the fullest I'd have to have custom dedicated filtered circuits and $1k a foot cables and interconnects.
For myself, Frank's product line represents that invisible line of performance/dollar that I won't cross because I can't justify the marginal gains (if any) of going further up the cost chain based on my listening, and I would bet the same is true for many of the normal audiophiles out there. I've kind of relegated those botique brands to the "guys with too much money and it wouldn't matter if it were $20K" type of shoppers. In the end, its totally up to you, but I think the AVA setup you are looking at is truly top of the line, and the only reason to go elsewhere is you hear a significant difference in sound or you need some sort of functionality/stylish design he may not have in his system (like auto on etc).