Neither C63 or M3 are "track" cars. If you want to track it, get the "real" M3, that kicked Benzes butts on just about every track you can think of, the E30. The C63 is more like a guided missile for shooting down the bahn and the M3 is moving in that direction. Item, the brakes on the new M3 are said to go away after just a lap or two.
And 50 year olds don't always drive luxury cars just like 20 somethings don't always drive ricers. My wife hates my modded EVO MR and AA supercharged
E36 M3 and I qualify for Sr. discounts next year.
With Benz poor reputation for reliability I would go with M3 but wait til 2010 to make sure BMW takes care of any issues. Look at the E46 and the problem with the engines that made BMW give that addl. warranty on the S54.