Team 131 C.H.A.O.S. at the GSR had a different sort of roller manipulator. They dubbed it the chainsaw. You can see it in their teaser:
http://www.youtube.com/watch?v=mXzGe-eDVLU
It's essentially the bottom part of a roller claw, but longer. The chainsaw goes in the center hole of the tube, then they just put the chainsaw right up at the scoring peg and reverse the roller. They seemed to have quite a bit less trouble with dropping off the tube than many manipulators.