Re: Prop Damage
The name of the game is balance between all of the blades and symmetry to the hub for desired smoothness of operation.
If you have a prop weighing 15 lbs, (as the big ones do) I really doubt that (can't possibly see how) filing little nicks off affects the weight. I have done it many times.
Now if you had a dog eared blade, that could be another story.
But the engine will usually tell you when it's out of balance. It will vibrate and sometimes vibrate the whole boat.
But, from a mechanical standpoint; the lower unit is one tough cookie and an out of balance blade will have to be really bad for a really long time before it would/could wear out your bearings. I think your steering and motor mounts would suffer the most.
HTH
Mark