The X6 drive-train is slightly different in that the rear diff has the electronic torque control and hardware not fitted to the E70 (other than the X5M) so the handling is different to the E70. I found no issues in snow up to 6" deep with Winter Tyres fitted (on 19" rims) at the beginning of this year.

__________________
Me:
Current: 2011 E71 40D Vermilion Red/Beige Nappa

Wifey:
Current: 2012 R80 Countryman SDX Green/Cream