PCM isn't as big a bonus as it was 10 or 15 years ago, when we used "wide band" systems. The older systems were more easilly interfered with, and there were fewer legal frequencies 20 years ago... (with cars and planes sharing frequencies back then.)

The advantage of PCM is the computer in the RX which can reset your aircraft's controls to a predetermined configuration on loss of contact between TX and RX. If set correctly, it can give several seconds for control to be regained before the aircraft is not recoverable. (before it hits something) its probably not worth the expense for use in a trainer... It can be very worthwhile in a $10,000 value competition scale model. Somewhere in the middle there's a point where it is a "break-even" by preventing one crash.

I have a PCM system... picked it up used at an estate sale (within the local club, at a meeting). I probably paid too much for it... but the guy had been a member of our club, and given the club a LOT of support. Everyone paid top $ for what was for sale. I like the system. Lots of cool stuff to play with. (There's a bit of computer geek in me too...)