Well as it a neat idea what I see is.
1) if your wheel is not in line with the object you anchor to,what happens to the line.
2) open differential will send power to the wheel which offers the least resistance, so if other wheel starts to spin you loose any movement from this type winch.
3) where you going to keep it.
4)
http://www.smittybilt.com/gen2_winches.html
Hard to beat a real winch that is,how often do you need a winch. Are you going drive less cautiously with a winch, because now you can get unstuck? The Edsel was a neat car I saw one today.
Russ