To give you guys something cool to watch and illustrate the point a bit better, here you go. This is the type of driving that I am talking about. The Audi torsen Quattro system feels almost identical to the older 50/50 torsen subaru AWD systems.
For reference on their channel they have an AWD mini cooper with a similar but reverse setup as BMW xdrive. Front powered with haladex clutch sending power to the rear. Similar to BMWs Xdrive that is RWD and uses a clutch to send power to the front. Point being it's an electronic reactionary system vs a mechanical proactive system. Reactionary systems are tough to predict when your messing around with left foot braking, weight transfer and stuff like that in slick conditions.
Not knocking BMW at all, it's just a different system designed more to get you home than anything else. I imagine after a few hours of sliding around you could overheat the transfer case oil in the xdrive and put it into limp mode.
For what it's worth I'm actually heading back to Team O'Neil Rally school this weekend with the 335 and will have plenty of time to play around with it again. Frankly the Xdrive annoyed me enough that I used Xdelete to turn it off and run it RWD. I've also coded off a lot of the throttle cut and braking systems.
With Blizzak WS90s and 100% RWD it does a great job in the snow and is pretty darn predictable. A rear mechanical LSD would be even better but not sure I want to dive into that.
If I were to do it all over again, I'd just get a RWD and run good snow tires in the winter.