I've always used them. The only problem I've had is the plastic "tape" inside. I would use that tape to "hitch" the bushing in place. It wouldn't take much to cause that bushing to fall out. The solution was found in a short piece of tie wire. I would slip about 4" of a 10" piece of tie wire into the end of the MC, and secure the bushing by winding the tie wire around the MC just like when using type AC cable. It really works well, and there is no harm done to the insulation. Necessity is the mother of invention.
Regards,
Doc
