OP: Lol, I am going through the same ordeal right now for the most part with a thread right next to yours (
http://www.m3post.com/forums/showthread.php?t=704756)
I have driven in the last two weeks a 2012 991 911S, a 2012 650i (as close as I can get to the new M6 until it comes out), 2012 Jaguar XKR-S, 2011 GTR, and a 2012 Maserati Granturismo S. Its a hard decision and seems, for me, that there is not a car out that I don't have to make some kind of compromise on when comparing it to my 2011 E90 M3. The M3 is legitimately such a good car, its hard to beat!