Holy cow, Mike and I agree on something!
I too, support "helping those who help you" so long as YOU, the assignor, feels they are capable of doing the level of ball you are asking them to call. I know several guys who work in this state that call great games at 10U and 12U, or work excellently at Leagues, but I would feel nervous about them working 16U/18U or extremely competively "A" games.