Having literally traded in an A5 a week ago for my M3 - yes, you are creazy ;-) Granted, the RS5 is a vastly different beast than my A5. The service/dealer situation was pretty awful. BMW dealers always seemed to jump to solve any warranty issue, and I would have to twist the arm of Audi service the two warranty issues I had. I could never shake the idea that I had, essentially, a dressed up VW.
Audi is still #2 in my mind for this type of car, but there's some distance between #1 and #2...
It's a *gorgeous* car though. Just angry enough above and beyond the already pretty A5/S5 design.