I have cut down wooden props but can you cut / sand down an APC prop without causing problems? 
In a word...yes
I use one of Jim Lee's prop scribes, mark off what I want to trim and rough trim with my disk sander then clean up by hand.
I cut down the 12.25x3.75 APC for my LA 46.
Highly recommend Jim's prop scribe for any prop wood or otherwise. It's simply the easiest way to accurately cut a prop down.
Later dude