It's been recommended to the BOD that the car be moved to FS along with the ISF and C63 effective 1/1/2013. It would be very unusual for the BOD to go against that recommendation. My thought is that it will be capable of winning everywhere in FS, but not an overdog. The Shelby GT (4.6l car) is lower, stiffer, and about the same weight, with the same tire, and better front camber. The 2012 is essentially the same weight has more power with 19x9's and more clearance than you would ever need but is just as floppy as the M3, and it's wide. Both Mustangs have better thrust in gear at 35mph but they're both stick axle which is a handicap on corner exit if there are bumps. Based on Matt Murray's results in the 1M, the M3 is probably not competitive in AS, though it's not totally useless either. I would keep running it either way.
It is a lot of fun to drive, very predictable but you can hoon at will if you want to, and place it really close to the cones with confidence. You can see from my friend's run that it's possible to break the tires loose anytime the wheel is turned, so it requires patience on corner exit but once you get to 100% throttle it really rocks on the high end, if you load the tires smoothly it boogies from 45mph to the limiter in a hurry even with the wheel turned, you can hear it in the second half (my run) coming into the last slalom. And it can carry surprising speed through sweepers. Slaloms are where the car is least happy due to size weight and softness
A good no-sunroof car is going to be a tough get. I wish you luck. I can tell you I do not miss the tech package at all, but I would miss the heated seats, fold-down seats are a must for transporting tires, and I would miss the homelink/dimming mirrors from the premium package