I did this last season. It's a nice drive, mostly highways, lots of police hiding along the route. It was a big blizzard, and the road was drivable, but definitely not salted or cleared as quickly as Ontario highways. I left Toronto at midnight though, so maybe that's why no snowplows were on the road. Shouldn't be a problem with AWD, but take the usual precautions.
Killington was great. Conditions can vary anywhere from slightly icy to nicely packed powder, or if you ignore the 'closed' sign, fresh powder.