ORIGINAL: RCKen
Fastsky,
If you are going to use your existing receivers then the decision is already made for you. It will be more than likely that you will have to go with the FM version. The PCM radio requires that you use a Futaba PCM receiver. I'm going to take an educated guess that the current receivers you have are not PCM. If that is the case then you will need to get the FM version of the radio.
Ken
That's not correct. The PCM version is selectable between PCM or PPM (FM) modulation.
I wonder if the 9CAF and 9CHF are actually on 8-channel radios... The 9th channel on my 9CAP is only available in PCM mode; and even then, it is limited in that it can only be assigned to a 2-position switch (On/Off).
***EDIT***
After doing a few minutes of research, the response immediately before mine is right, there's only one version of the radio, and it works in either PCM or PPM modulation.