aha yea me and a friend built a winch last summer out of a pocketbike engine. Our intention was to use it throughout the winter for urban, but we never actually got around to using it because its fairly heavy and awkward to carry.
That being said we did use it in the summer for a set up in my backyard and it was really fun. Hopefully next year we'll use it some more.
But I definitely think that winches will let you hit some really cool urban, especially bigger stuff instead of having to build a drop in or find a hill.