I use PPM with my gassers. No problem.

PCM and PPM both will get interference. The difference is how each will react to it.

PPM will act like the plane is being hit.
PCM will go to a fail safe mode. If you are not asking for a control input at the time you may or may not realize your having a problem.
You are able to set the failsafe mode to whatever you want but most people I know use the default setting of throttle to idle and controls neutral.

I watched two planes this year go into the ground during a PCM lockout. (failsafe) so to say that its less likely to be interfered with doesnt hold water with me.

Both are good systems. You need to decide whats the best for you.