Remember the quote from Glenn in post 45 -- the reference to human factors. That's a real issue with the Sherpa. Why?
Human factor engineering is about designing things in a way that considers human capabilities and limitations to reduce the possibilities for operational errors, especially under stress, and to reduce training requirements. The Sherpa doesn't seem to do that well.
While it is possible to train to use the Sherpa properly and safely, its design makes it especially easy to make a particular, natural and predictable operational error that is dangerous to the user. If you are really good at using it correctly, that will be fine. But it is designed and operated in a way that makes it especially easy to make a particular mistake that can get you hurt.
"It is long been a principle of ours that one is no more armed because he has possession of a firearm than he is a musician because he owns a piano. There is no point in having a gun if you are not capable of using it skillfully." -- Jeff Cooper