Pathfinder has a similar take on it that I do. It is very dependent on the area. I hunt one area where the deer stay high well into December, but they have a lot of browse in that mountain range. No need to come down until they really have to.
In another, the does are all low by mid-October, and the bucks are at or a bit above mid-mountain and they don't come down until the rut. They'll plow through belly deep snow mid-November on the way down. Again, there is enough to eat up high, so they stay.
One other area is pretty dry, and all the deer move down at the first hint of snow, or by the first of November at the latest. There isn't anything up high to eat after it freezes. The bucks stay higher, but not like in the first two areas.
Jeremy