But you do have a choice, you can use the IPD receivers from Multiplex.

First if you have problems with PPM, you should fix the problem first, because the problem would still be there with PCM, only you wouldn't know about until it locks up.
The main reason to use PCM, was because of the fails safe, but now the IPD's have one of the easiest to program Failsafe or hold.

I have a bunch of PCM receivers in a drawer gathering dust and will never go back to them.

BTW, Multiplex which invented the PCM's, stopped producing them in favor of the evolutionnary IPD's..