Keep in mind that OS specifically does not recommend a large dia. low pitch prop for the 91FX. They suggest 13x8 and 13x9. IMHO it will be more than powerful enough for normal aerobatic routines. If you plan on flying 3D and swinging a big prop, then maybe other engines would be better suited.

9C is a wonderful radio and is what I have. With this type aircraft, you can easily program for the dual aileron servos simply by enabling the flapperon mix. This way, you can use the subtrim function of each channel to set the position of each aileron half just right, and also dial in the right amount of aileron differential, if required. You don't necessarily need the flapperon function, but enabling it make programming very simple.