I am fortunate to have both a 99 SVT and an 01 S4 Avant currently in my garage. The build quality, as you would expect, of the S4 is so far superior than the SVT it isn't funny. It seems to me that you get better driver inputs and feedback from the SVT, you feel very isolated in the S4. It is a heavy and safer car than the SVT, if your in an accident, the 8 airbags is comforting. I track drove the S4 last weekend at Brainerd MN., simply the car hauls a**. I did warp the front rotors- a common problem in the car. The power comes on smooth and steady over the rev range. Bottom line- great car- but for 40k new, it better be.
Enjoy making your decision.