Hey guys, I just found the thread and will need to read through it, but I figured I'd chime in with my thoughts.
Mid-year I decided that I needed something with torque and decided to jump into FS with a 2007 Shelby GT. The Shelby is awesome to drive, and FS is an awesome class, so I plan to stay. However, I'm considering a DD replacement and the M3 would be an awesomely fun / nice upgrade over my BRZ. As such, I'm considering the FS prospects of this car.
As I see it, many cars could have won at Nationals this year (mine included). Brian in the 2011 GT along with James and Matt in the E46 M3 ZCP all had the speed to win. However, I think the 1LE will prove to be one of the faster cars if not the fastest car in the class (Dave was running with very limited prep, due to parts availability that should open up soon).
With that said, I don't see how an E92 won't be faster than an E46. Now with the Boss 302 in the class, my perception is that the 1LE, Boss 302, and M3 ZCP will have a slight advantage over the rest of the class. I think the Boss 302 is a fairly safe assumption since the 2011+ GT has won, and I don't see how the Boss 302 is slower. The M3 is the unknown though, although I know it did well in 2012 on Hoosiers.
I don't expect the 2015 Mustang to be much of a threat - it has grown to be the width and weight of the 1LE Camaro, but only has 9.0"/9.5" wheels and is handicapped by mandatory 3.73 gears.
I'm now kicking around the idea of the M3 and the Boss for autocross use (obviously there are other factors but just thinking autocross for now).
The Boss will be the fastest car in the class point-to-point and off the line IMO. It has a high enough redline to make 3.73's work, which will give it 66mph in 2nd but crazy acceleration (MT tested it at 3.97s 0-60). It is softer and heavier than the Shelby though, so no advantage there.
The E92 M3 is narrower than pretty much everything except the E46, and lighter than everything in the class except the E46 and the Shelby. The real question for me, having not driven one, is if they have excessive understeer during sweepers. What are your thoughts on that?
In other news, for anyone who needs it, I believe this is enough documentation to allow for alignment pin removal:
http://www.m3post.com/forums/showthread.php?t=1041105