I've used both, the ATB is much more civilised for the road - no snatching, banging etc when the preload breaks away, and no need for continual dismantling to maintain a constant preload as the plates wear.

On the loose though, plate type works better, as it does not rely on both wheels having a degree of grip to work, the plate LSD will drive one wheel with the other completely unloaded (I'm not telling u Mark - I'm sure you appreciate this already!! )