Really depends on where your flying.
When i started flying in kansas, lots of people were having fits with FM, supposidly because of a pager tower nearby. So i started with PCM and havent looked back. Since moving to Dallas, then Houston I havent seen anyone have trouble with FM like i did at that field in Kansas.

edit,

I do know that with my Futaba, if someone flips on their FM TX, it wont touch my PCM RX.