My LG neoprene covers held up well all last fall (cold and wet through Oct/Nov) and this winter. No significant damage and limited wear not affecting performance. +1 on Carbonfiberboy's comment about not walking around in them, especially on gravel. I think some people buy them too small and then overstretch them. If they are hard to put on, get the next bigger size.

I should note that during the very coldest weather, I switch to insulated, waterproof/windproof hiking boots and don't clip in, so my covers might not get some of the mid-winter beating others may.