I have shot a lot of animals with mechanicals (30+) but I really don't see the advantage to using them with the quality of fixed blade heads available, such as Slick Tricks, G5 Strikers, etc.
One failure of a mechanical head in a hunting situation is too many. Shoot them long enough, and kill enough animals and it will happen. I will just not take the risk anymore, not the way my Slick Tricks perform, flight, holes, toughness, etc.

Dan