We've got both now. I'm keeping the E90 M3...for good, but that was already planned. The M2C is my wife's main car, and we've put almost 1700 miles on it already. I took the car to a wet skidpad event at Michelin proving grounds, where I've had the M3 before, and
I did a write up in this thread. Further down in that thread I did a brief comparison to the E90 M3. We've been so busy I've not had a chance to drive the M3 again since that day, but my wife and I are planning on taking them both out for some rural road back-to-back driving this weekend.
It's a entirely different experience than the S65. The S55 is a beast in this little car. If the S65 experience is a scalpel, the S55 is a butcher's knife. One thing I can say for sure is that they have massively improved the electric power steering -- by far BMW's best effort to date; see my write up on that. If someone said "you have to sell your E90 M3 for an M2C", I wouldn't be crazy upset as it's a fun car, and the seating position is superior to the M3 (wheel telescopes a lot more, shift is closer to driver), and the seats are fantastic. I'm glad I don't have to make that choice.
Cheers,
Chuck
P.S. Wait a bit and buy from a dealer that does a lot of out of state sales...we got a $1117 discount off MSRP. We were on the list at my local dealer for MSRP, but our allocation spot wasn't going to come up until probably Dec or Jan, so this one appeared and we bought it right away since it was exactly what we planned to build: LBB, slicktop, Exec pkg, 6MT.