Very nice numbers from the MTM S4! However, regarding character, I think its a deliberate choice. Indeed, those who tune Audis typically seem to be more into engine and exhaust modifications than suspension tuning as far as I can tell - I think a full fledged MTM S4 with revised suspension and brakes and the sport diff would be much closer in spirit and performance to a RS car than only a partly modified one. Of course, you could in turn tune a RS car to be more hardcore also - but the character seems to be more by typical customer choice than intrinsic to opportunities.
Slightly off topic, MTM or other tuning and those of you who have bought it: do you worry about durability and resale value? I am asking because I once had a MTM re-mapped S3 and while I really loved it, it was sadly not exactly an advantage when I finally sold it.