Just tried out the rattle wedge last week on a cook pine removal. The spar had a mild lean, given the access, I needed to rig and coax the blocks into falling on the backside. The device worked as intended, and the ratcheting action was slick, but in that situation I'd take a rope and a groundsmen anyday. In my book it is cost prohibitive considering what you get out of it.
Here's my R & D, Make it out of hard plastic, double the size, and cut the price. the cost could be severely diminished by ditching the ratcheting action, which is a convenience but by no means a necessity. If that where to happen I would think this would be a product I would invest in