At a contest, fly in, or at the local field, its the AAAHHH! factor. Just starting the engine with a home made prop puts you into another league. The ones who know it is too small to be scale also know physics makes it that size, and the ones who don't understand that just think its cool. Your the hero both ways. Having an APC prop on a scale plane is about as pretty as bird poop plopped on the plane.