2.4 GHz receivers by themselves are perfectly fine for Glow and Gas powered airplanes. What the Techs may be worried about is the use of 2.4 receivers with built-in gyro/stabilizers. That is a big NO NO! The solid state accelerometers in these units are not designed to withstand the high frequency vibrations found in glow and gas powered airplanes and will eventually fail causing the loss of your airplane unless you are quick enough to switch off the stabilizer at the transmitter before the crash.

Bottom line: 2.4 Receivers OK. Solid State Gyro/Stabilizers NO! (Unless built specifically for Gas/Glow operation).