From experience, I rarely use ... sometimes in the snow if is a bit sluggish and [s#} a bit much!!! Not entirely convinced re the VDC making a difference. C-Diff? In the dry... manual, all to the back... Manual locked in the snow (unless manoeuvering!!!!). In the wet, Auto, Auto -.
Best advice... have a play about with it and see what suits your driving style. No point in having adjustability if it's you that has to adjust rather than the car... follow? *chuckle*