It’s been only brushless since I got in hobby in late 2010. I do own a few running brushed but not for any particular reason other then they came that way, liked how the ran. So I only know the stories of the old brushed days. Simple reason I’ve come to understand it’s they are overall simpler and far less maintenance then the old brushed motors. Hopefully those with experience from the brushed days will respond.

Most of your question I know I don’t understand what’s being asked.