[flameout]

We also considered this idea, and got a prototype built, but we decided it would not be reliable enough for the robot. The tape can snap and fall, which would require us to pull it in and start again. Also, we were thinking we could use it as a winch and an arm, but it doesn't seem strong enough (directly, it could life >500 lbs., but any bending/attachment methods weakened it.)

By all means, however, go for it -- it is a much simpler idea than most, and could turn out to be a winner.

Good luck.