Just sharing some info about the early e53's with the 38/62 torque split and how
DSC-X works with it. My belief (again) is if you are experiencing lots of wheel slippage/spin in snowy/icy weather...the issue may be more about the type of tires you have mounted moreso than the ability of the AWD system.
The traction control systems kick in when there is approx 5% wheel slippage...dedicated winter tires in harsh winter conditions inherently provide better traction as well as better stopping and handling in terms of being able to turn etc.