I haven't got PSM, and from my point of view it would probably help driving in rain and snow. But considering the fact that cars didn't have any sort of traction control until a few years ago, it does not make a huge difference. I enjoy my spirited driving without the PSM, and in conditions when it might help me from spinning off the road, I'll just slow down. It is no big deal, just tame your driving to fit the road conditions.
And in response to boxsterz, what your getting at is that PSM boxsters can go faster on twisty roads and in poor road conditions. But who cares about speeding up the mountain in the snow, or speeding up on an average day. Unless your racing someone it doesn't matter and if you were racing you probably would be professional enough to turn the PSM off.
