....As far as I can understand it (I'll know more after my session with VWR at Bruntingthorpe on Friday), if the Mk6 LSD system is electronic or uses the ESP, there is a likelihood that the ESP will think for you and not always make the desired choice or as quickly as you want it. Whereas the Quaife system is more reactive to the physical state.
However, I don't know and am guessing at the present time.