The 911 in experienced hands that know how to use the 911's handling attributes will come out on top. My .1S had the same feeling of the front end bouncing around, but as others have said the .2S really dialed a lot of this out. The grip from the rear of the car is just phenominal vs. the M3. I find the M3 is looking for traction all the time regardless on how good the diffy is on the car. Even with larger 285's out back on my M3 it is easy to drift the M3 while the 911 you really have to be hamfisted to get the rear end to come around.
Slow in and fast out is the way a 911 is to be driven. You are on the gas earlier on exit than you would be in an M3 and you are blasting down the straight away.
2013 M3 Coupe-MR/BLK ZCP, identical to my 2011.
2011 M3 Coupe-MR/Blk
2007 Porsche 997C2S Speed Yellow/Blk sport seats
2004 BMW M3 Imola/Blk