Not looking to be blasted for this, but on a steep hill nr me in the snow I don't use HDC. Used it once and I found that it would let the car roll up to its set speed then start breaking the wheels. However it brakes them sharply and looses traction and after a few meters of this had all the wheels sliding without control. What I do now is use gentle pressure on the brakes to keep the car slow and the wheels turning at walking pace so i can maintain control (rather than the sudden on off braking of the HDC). However..... I try not to go down that hill to often in the snow and it buttock clenching stuff.

rjp,I think you have hit the nail on the head,I will never use hdc just the weight of a FF will make you skid/slide with too heavy braking or too lower gear on ice/compact snow. after 45years of driving hgv vehs. i have found the method that suits me in those conditions is lowish gear and just feather the brakes and keep the wheels turning.