I agree wholeheartedly with powell. The BionX system is a system, not a bunch of independent components put together (or partially put together) in a haphazard manner. Perhaps most important, as powell points out, the BionX system has been programmed extensively to provide the rider with an integrated and modulated power assist experience, plus a throttle assist when desired. I have about 500 miles on my BionX package and could not be happier. I've only had a couple of minor issues which were easily dealt with, even by a klutz like me! It is definitely more expensive than many alternatives, but in life you generally get what you pay for. For me, the reliability, the smoothness of the assist, the silence, and the unobtrusive nature of the whole package is very satisfying.