Personally I would rather have the double click feature because:
1. Double clicking isn't that much of a hassle.
2. I have had fences all over my desktop and I wouldn't want them appearing because I accidently went near the edge of the screen.
I'm not saying your idea is a bad idea. Its actually interesting to think about and I would like to try something like that. But I think there should be a CHOICE between auto hide and double click, or possibly both.