There seem to be a couple of points of confusion here, perhaps I can add to it!
First, I'd be very surprised if the defence force ones were deliberately flown outside flight manual limits.
Re the reason some defence pilots didn't like them; as I heard it, at some flap settings, bad airframe vibrations occurred and basically guys refused to fly them for that reason.
As I understand it, the tragic South Aust tailplane separation accident was attributed in part to stress from lengthy high power ground running for test purposes in combination with some deficiencies in airframe inspection procedures.