^ Note that I have driven my father's '06 M5 with the SMG. Not a happy experience.
My anecdotal story:
Sitting on 3rd St, waiting to make a left turn into a Thai food restaurant. Had a small opening, and thought... "400 hp should be good enough to gun the gap!" Yes, I was driving it in normal mode, not having pressed the 500hp button.
So I floored it. It rolled from a stop out into traffic. Kept my foot on the floor. It kept rolling. I stained my shorts as I watched the oncoming car get closer and closer.
As the oncoming cars are now emergency braking to avoid broadsiding me, the M5 finally went fast. Very fast. Straight into the Thai restaurant parking lot. Shorts stained second time, as I executed an emergency stop before having a parking lot collision.
Bottom line... I am a control freak that does not trust slushboxes (or SMG or whatever takes the third pedal away from me). My experience in the M5 deepened my distrust.
Stick shift, or die.