I don't think taking material off the hub is a no no. I scrape off the flash as part of balancing as it's not really supposed to be there anyway and if it helps bring the prop into balance anyway then no harm.

As a more general philosophy, I think with all the info on the internet, a lot of people talk like they take things to way extremes as if they're working to tolerances to send a probe that is launched with the precision necessary to make it to the nearest star with no course corrections possible during the journey and have to arrive within a target of a square meter.

When I see people's piloting proficiency at the field, the talk on the internet isn't even close to being backed up.

Close enough with prop balance is close enough. If the plane isn't shaking apart and your servos aren't being destroyed then don't lose sleep over it.

And by the way, nobody here should be offended by my comment. It was a general observation and not directed at anyone in particular. I fit it just as well as anyone else.