I tend to agree with Mach Jump, the extra flap movement will make no difference at all apart from putting the aircraft in the hedge at the far end of the runway because your hand is in the wrong place to get the power on for the go around.
As for 18 Greens pitch change demo, rather than demonstrating what you should not do, I would have favoured teaching the positive aspects of slowing the aircraft to about 70 KTS before deploying any flap thereby avoiding an uncomfortable amount of pitch change and being gentile on the aircraft.
As to it being a good trainer, it is an adequate trainer............ The C152, PA38 & DHC-1 are good trainers.