Hi,
Actually there is a slight difference when the receivers loose signal. The FM receivers stop sending position pulses to the receiver. The PCM receivers keep sending position pulses, either the last position, if the failsafe was not set, or the failsafe position. The was a small mistake in the firmware that got past testing that did not shut the motor down on an FM at loss of signal, the PCM works fine. Since a batch of units was made up and the firmware is hard to change we modified some to do the right thing with FM and left the PCM versions as is. This will be corrected on the next revision due out soon.