I thought I could have easily mistrained my pup to be aggressive, from his reactions to traditional old school methods, that worked in past with other dogs. So it's not just "sensitive" dogs but the apparently less sensitive hard to curb, won't back down ones to.

Having fostered his sister who's had to be rescued, she actually soon showed some aggression issues after a few days of R+, so I'm even more sure of it once the fear of intimidation was removed. It's no good suppressing behaviours if you don't instill the positive ones you want, and generally soceity seems to love punishment and discipline (for others) more than real coaching, patience and teaching; so I'm now convinced by the consensus.

Even now, the people who had most trouble training their dogs, took the longest, advise me to copy their methods (obviously as they had so much trouble subduing a wilful dog they are experts). None of them seem to be questioning their approach, despite younger dogs being obviously sucessfully trained in much less time, with manners issues left mainly caused by playful exuberance. I guess psychologically if you spend a long time doing something, you cannot question it as easily as something you just tried for a short while.