Hey I use GT to pratice for rallycross, I don't know what driving on snow is like, but I like GT's sim on dirt. I have to say the feeling of the transition between the dirt and pavement is pretty good too (like Cathedral Trail 1 or Tahiti Maze). Maybe you're just taking advantage of the collision behavior too much.
Anyway I haven't done any laps since trying those few laps last week, and probably won't have time to do any tonight either. Playing GT4 is major effort since I have to drag the WRX seat out of the closet and clamp the steering wheel down and go through the whole production. I don't have a convient setup like Gary does