it's pretty much like, if your car isn't a professional race car (i.e. every single person on this board) then stop fretting over your exact specs and times. go w/ whatever feels more fun to you.
i honestly don't believe that BMW would release a car w/ a transmission that simply cannot stand up to the engine's power. just get whichever one you want more (which should be a manual since you want to have more fun driving around at speeds under 80mph most of the time