I think the important point of the DSC/traction control 'discussion' is that if I had Xdrive I would have a better chance getting through a mud pit or getting around a curve instead of going off into the woods.

Limiting this post to braking of a wheel(s) and how fast a wheel is turning----

The original system does split 100% of the power mechanically--can't change. The front wheels spin with 32% of the available power and the rear are pushing with 68%, all the time, in all circumstances. When the fewer sensors of the original system indicate I have a problem it will brake a wheel or wheels. The same percentages (32% front, 68% rear) of the total power available is still going to each end. It is just that the braking system is restricting some percentage of that power from getting to the ground at one or more wheels. No matter the input of the monitoring sensors, no wheel is spinning faster than the mechanical split of total power. The resulting assistance can only make a wheel(s) spin slower.

The Xdrive has more sensors so it would add more talent to mine. The Xdrive system also regulates the power to wheels electronically rather than mechanically. That's the reason for the clutches. In theory, one wheel could take 100% of the total available power. Xdrive can speed up or slow down any single wheel or combination of wheels.

A very talented driver on a road course will go faster without either system. I turn it off if I want to know if my commitment ends before the grip. For maximum straight line acceleration I shut my system off. I would never turn off either system for day to day driving.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas