I was impressed with mine (same Plus 66's as yours) when we had snow down here on Wednesday - and I didn't even need to go anywhere; I just went out to see if they were any good! The only issue I had with them was black ice on the main roads (traffic was moving enough to have turned it from white, but slowly enough that it was re-freezing to the glossy, glass-like ice), on which that even very gently bringing the throttle in, crawling along in stop/start traffic, would see the N/S rear tyre spin a little making the back end tramp a touch before it gripped and went forward. I think though that's down to two things; 1) you can't change the laws of physics, and 2) the Torsen LSD that's in the back of my IS isn't the best type of LSD for slippery surfaces (something to do with them needing some traction to "fight back" effectively. Torsen is good by being virtually bulletproof, but on slippery conditions (snow, icetrack) it will not perform like a cluch-type LSD. If you jack up the rear of a car with a Torsen LSD, and turn one of the wheels by hand, the two wheels will spin opposite directions, unlike a clutch-type LSD that both spin the same way)

Either way, it was still way more driveable than I'd expect it to be with regular summer tyres on, as proved by pulling out of my parking space and up the ice-clad hill/slope to the main road like there was nothing there, while Beemers and Merc's were dropping like flies