You'd be surprised at how little wind you really need. It scales pretty well with the weight of the rig, and like I said in my first post, my 14sqft sled is more than I need to a lightweight rig.
I love the simplicity of the kite, but it just won't work in my topography. Average wind speed is pretty low around here. It also tends to be really gust and changes direction fast. Also, you have limited areas to go up. If the wind isn't blowing directly down a road, or out onto a lake, the kite will just get blown in to the trees.
Anyway, cool stuff. Nice and simple.