From an instructors point of view it sure is nice to just release a spring loaded button and have control of the plane than have to worry about flipping a switch. That little extra 1/2 second could be the difference from continuing the flight and getting out the plastic trash bag. I don't mind holding the trainer button, just wish they all where like a toggle switch on my Futaba 7C instead of the stupid little button JR puts on some of their radio's that is hard to get at and pain to hold down sometimes.

Hogflyer