Came back home in about an inch of snow last night.
Very reassuring to have four wheel drive and quite fun to weave left and right, the front wheels sliding a little, yet feeling completely in control.
The (very scary) surprise came at the end of my road. I slowed down to less than 10mph and, curious to know how the traction control would behave, squeezed the brakes a little harder. The ABS kicked in.... but the car kept on going forward almost as though I wasn't pressing the brake pedal at all. For a few seconds I really thought I would hit parked cars at the end of the road. Fortunately, I did stop in time, but only just.
I read afterwards that ABS is known to increase stopping distances on fresh snow. On reflection, this does make sense - each time the brakes are released after the wheels lock up, the wheels immediately skid again and lock up. Also, snow doesn't accumulate in front of tyres in the way it would without ABS.
Somehow I didn't expect this to be a problem in such an expensive car, especially as deceleration is so good on fresh snow before ABS kicks in. I have learnt my lesson now.
Anyway, be careful - the Q5 is not invincible!