Here's a tip...if you have not tried a 11.5X4 APC I suggest you do so before you comment on what the best prop is for a given engine.

Sure the 12.25X3.75 is a great prop and preforms fine. What your missing however, is the spool up time. Think about it. A shorter prop spools up quicker.....what do you want in a hover?

A prop that responds as quick as possible, ergo the 11 inch VS the 12.25 is a no brainer.

Just try it, then comment on your objective results.

Besides, since when do you only have one prop size in your prop collection?