The Schottky diode isn't mentioned with some ESC suppliers. The reason for the diode is to prevent the "back EMF (electro-motive force)" which in other terms is the electric power generated by the motor. The motor, even though it provides labor is also a generator in a small form. Somehow that affects the ESC (not an electrial engineer), the system will operate without the Schottky diode, its just that the mfr's feel is protects the ESC from electrical spikes and in their words "makes the ESC more efficient and run cooler". Since the diode is provided with the ESC I use it. I also noted the use of two diodes and I need to take more smarter pills to know the effects of using two diodes. The only thing I can think of is that perhaps if you are turning a large non-folding prop there may be some motors that "free wheel/pin wheel" and generate excessive voltage back into the ESC. May be a problem with large motors also. In any case the Schottky will not hurt the operation of an ESC (unless it isn't installed correctly, HA), and actually it is a benefit for longer life. 'Nothing like the smell of an electrical fire in the morning.'