lets see......i tried 12.5x3.75 and didnt like it even though a couple guys at the field swear by them.i tried a 11x4 and it was great but the hove was too touchy.one more click and it goes up on less click and it comes down.then i tried a 11x5.that worked great untill i tried a 12x4.tons of power but it loaded the motor too much and i could only hover for a little bit before the motor got too hot.i broke my 12x4 landing from a harrier.put the 11x5 back on and the knife edge disaperd!but the climb speed was better.the 12x4 pulls out of the hole but the climb speed is so-so.went all over the place and finally found a LHS that had 11.5x4 in stock.NO THATS A PROP!!!!hover is smooth with a couple clicks were it will hover........the pull is good........knife edge came back and the climb speed is awsome.all props are apc and the motor is 46fx on a 5lb sig se.hopes this helps
good luck