a quick bit of info for the 12" props, I bought them bored to 5mm and a lot of us have 6mm prop shafts. i'd recommend balancing the props before reaming them. when you go to ream them do it in as many small steps as you can to keep the hole from moving. if you go right to a 6mm drill or reamer the hole will move in the soft wood. i used #7, 5, 3, and 1 drills before putting a 6mm reamer through the hole. also, I couldn't get the prop in a good position in my drill press vise so i held them lightly on the bench and let the prop guide the bit to keep me from running it out of center. i even let the prop up off the table as the bit started to bite into the wood and then just held it lightly as the drill did its job.
the standard CW props seem to be harder to balance than the CCW props, i'm curious to hear others' experiences with that. if it's bad enough i'll bring it up with the supplier.
have fun,
bart