Maybe I didn't phrase that correctly but it's not an urban legend. I use Futaba and have tested this myself. With a second Tx on FM it won't affect the PCM Rx on the same channel as long as the PCM Tx has a strong signal and a good charge in the battery, otherwise it will cause a failsafe mode. I suppose just like most everything in this hobby, it's what makes you comfortable that matters. I have seen a couple of planes get hit that were on FM and the pilots didn't have enough control to save their aircraft. I have also seen planes fly off into the sunset at full throttle and personally, that is what worries me about flying large scale on FM. IMO, anyone using PCM should program the throttle failsafe to idle. It doesn't guarantee that you won't lose an airplane but at least it has much less chance of flying to a populated area and possibly killing someone.