If you are looking for a DD that has a great power and even better handling out of the box then an M3 is the way to go. I opted for the SMG on mine (had an rps 6puck in the Z) which I wouldn't trade for anything, shifts smooth when I am just driving around the city but can break your neck in the proper mode (good thing) like next gear right NOW type speed. Maybe Randy will comment on how quick it shifts :-)
I do miss the power of the Z but don't miss the "How is the car going to run today" feeling everytime I would take it out of the garage and the Z was by no means in bad shape, lol. That last part may sound weird but take it for what it's worth.