i should clarify a statement i made in my first post.....i do not KNOW that the metal bell crank will hurt your tail servo gears any faster than the plastic one could. in my mind, the plastic part SHOULD break first. after reading everyone's experience with the metal one, sounds like that is really not a concern. not surprising if you think about it though, the carbon tail rod is very strong pushing straight back and forth, but lateral forces can break the tail rod easily, so that will be the failure point. the blades hitting the ground are really the only thing that can push the tail rod straight back and forth, and the blades themselves will fail far before the rod will damage the gears (again, in my mind....)
like i said, i fly both the plastic and the metal bell cranks, and they both seem to hold up beautifully.