I don't have the GC, but I do have the coupe w/CP, and I am absolutely running it on the track this summer. It's heavier than my old M3, but it's got good grip, good suspension, is pretty neutral in the corners, and I think with all the nannies turned off it will be a heck of a lot of fun
I'd imagine that turning with the throttle will be easier than in the M3 since there's ALWAYS plenty of torque, and the HP will make any straightaways a real blast.
I probably won't be the fastest guy out there, but it will be a ton of fun