I've had the pleasure of driving and owning various powerful beemas including the last mcoup, a 540, and a 330 and have always gone for manual. I recently bought I an auto coupe (3.0) and quite like it although it took some getting used to. The first niggle was going into a corner one likes to be in the correct gear for exit speed/acceleration away. If braking hard on the way in the auto box wouldn't change down with decrease in speed so there would be a slight delay when from the apex and u dialing the power back
In the box has to change down at that point whereas in a manual it would clearly have been in the correct gear before that point. This is solved though by changing down manually on the flappy padles or touring car style sequential stick function on ur way in. Next niggle (only happened a couple of times in sports mode) was the car changing down unexpectedly when balanced on the revs through long sweeping corners. Car obviously thought revs to low but I disagreed. No big deal. Just a bit of a surprise. The final niggle is that when u start using manual changes it doesn't leave you to it. i.e. No input from u for a while (seems like 1 minute or so) and it will revert back to auto mode. This is a bit annoying when for instance hooning down country roads in sports mode. When I get to a village/30 zone I change up so I'm not pootling through town with the engine at high revs on the bottom of the power zone (which is where sport auto keeps it). The car will automatically switch back to sport auto if I don't touch the box for long enough and change down one unnecessarily and without instruction. U get round this by switching sport off on entering village and back on when u leave. All minor niggles to be fair outweighed IMHO by otherwise lightening quick upshifts using full power band (sports mode) and general convenience intuitive shifts round town/in traffic in non sports mode. In all given the choice I'd get an auto again. Just wish when u put it in manual mode it would stay there until told otherwise and not switch back to auto of it's own accord. Test drive both and see what u think. Bear in mind will need to get used to auto chatacteristics but once used to the auto it's a good bit of kit IMO. And this from someone who has never touched an auto before on principle.