Originally Posted by swanseahammer
Why, apart from paddle shift, which I would use btw.
There's a big difference between the standard 8-speed auto and the Sport auto. The standard auto is probably the same mechanically, but the electronics are very different and it feels a bit sluggish and un-responsive. The Sport auto is a complete contrast, changing quickly and intuitively, just when you want it to. The paddles are a bit of a gimmick, but the response when you use them is so quick that it's quite satisfying.
I drove two demo cars on back to back, as the sales guy wanted to show me the difference between a 328i and a 330d. I drove the 328i first and it had standard gearbox - felt like a very ordinary auto and certainly not special. The 330d had a sport auto and was a joy - to the extent that it persuade me to order my first ever auto! The sales guy confirmed that the two boxes are setup very differently.
So I'd go for the sport auto without hesitation. It's better all-round, whatever your style of driving.
By the way, the 320d M Sport handles a bit better than the 330d M Sport - it's just down to engine weight but you can really feel the difference. If you can live without the grunt of the E90 335d, the 320d has a vastly superior ride and, much better handling and will make you grin in the bends.