Main difference is that with no torque converter the F1 style gearbox will not hold itself on a hill whereas a conventional auto will. That can be a bit of a nuisance. The BMW SMG gearbox gets around this by a mechanism triggered by holding left hand paddle (if my memory serves me correctly) for a few seconds which gives a further few seconds of hill hold.
I would love paddle shift on my S4 and believe from the factory that this will be introduced at some point.
With respect Robert, I don't think you have driven a Porker PDK-box as the game has moved on. It's a twin-clutch electronically controlled manual box (1,3,5 and 7th in one gearbox and 2,4 and 6th in the other) and it is just as good as a normal auto - at being an auto, as it holds it's position on hills, etc, having a degree of creep built into it.
However, as it acts almost as a pre-selector box (clever these electronics) and consequently, it is much faster than the ZF-autobox in the Aero both in everyday use and especially in extremis and imho has really moved the game on. It is much better solution than the F1/SMG boxes that the competition offers.
I have been told that it is in fact built by ZF for Porsche, I'm not sure if this is true, but really this is the box that the Morgan works need to move to, though whether they can now afford the development cost on their low volumes is another question.
