To me the fundamental question is 'if I take a fish - is it more likely to survive with QT (non-medicated) QT (medicated) or doing nothing.
In general, for most fish (>99%), I think this question has been more than answered.
I say for most fish, because I suppose there may be some very delicate fish that would have a hard time in the less than ideal QT environment. Seems like this should account for <1% of reef fish in the hobby.