Not as long as its got religious service history, full belt and oil changes at appropriate dealers/specialists etc
My g/f's uncle had a 911 (just the 2 w/d) and it was rapid, 350bhp iirc. Very capable indeed, he was telling me of the running costs and it genuinley wasnt as bad as you would think, there are alot of reputible Porsche specialists out there if you know where to look. He sold that 911 and conincidentally bought a 2003/53 RS4 (the limited edition 375bhp model)
I thought that 911 was quick but the Audi just inspires so much confidence with the Quattro traction it posseses.