I have Proxes in 235/45/17 and they are nice. My previous tires were Falken 512s and the Proxes are better in terms of being more quiet and have firmer sidewalls (for any given tire pressure). The 512s were better in terms of straight line traction, but the Proxes are better around turns, due to the stiffer sidewalls. Wet traction is about equal on both. I haven't had the Proxes in snow yet, but I have heard nothing but good reviews about them in the snow. Obviously, nothing beats some dedicated winter tires if we're talking heavy heavy snow and ice.
And btw, I have a pair of Blizzak LM-22 winter tires in 235/50/17 with low tread wear I'm looking to sell if anyone is interested.