Gee, I've used APC props for many years and not gotten a really bad one. I wonder... I use a Dubro teeter balancer that is good enough for 15K RPM on a 10" prop. Someone who runs higher RPM may want a more finely balanced prop.

Scraping the edges is good. APC props have a sharp flashing that needs to be removed. What I would be hesitant about doing is sanding the face or back of the prop. that might produce scratches that may set up stress line that could cause failure. If there's no danger of this, I wish a prop "expert" (maybe someone who works for MA or APC) would step in and set the record straight. If I did anything to the face or back of a composite prop, I'd scrape, not sand.

Dr.1