I put of getting an M3 for years because of the same lack of shove in the back feeling. I needed up just buying one anyway just because it was the last opportunity to get a new NA M3 sedan and figured I'd have to live with the lack of perceived oomph.
Trust me though. Once you actually drive it for a few days you will find there is plenty of torque to be had, it just takes more throttle input to find it.
There is no way you would regret the M once you have it.
2012 AW e90 M3 DCT - Daily
2010 AW X6 50i - Tow rig/baby hauler
1991 Nissan 180sx SR20DET - Drift pig