Do not use single conversion for combat!!!! the vibration and speed make a combo that will ensure loss of control. The electron 6 is a good choice for FM. Make sure you install the crystal rubbers to make sure you do not have any crystal problems. I have used the AR 6100 and the 5000 for 2.4 and the both work great. if you have older AR 6100's they should have the fast connnect update. Spektrum also is prone to low voltage brown out so an appropriate battery is in order. I have also used their plug in capacitor (with the car stuff) to avoid low voltage brown out.

Some Cheap off brand stuff will work and guys are using it, but I try not to skimp on the control end, you get what you pay for. Open B planes are about 90MPH, out of control even for a short time can be devistating.