BMT
I could not have put it better myself, PCM every time.
There may be special PPM sets that 'apear' to offer what PCM offers but we are talking about normal field flying with the most prevalent brands (Futaba and JR).
What is available is PPM and PCM, what is best is PCM.

No mater what the theory, try a simple test. Get 2 sets of radio on the same frequency (on the ground!) One PCM one PPM.

Switch them both on with both ariels down. The PPM set will be all over the place, you will still have control over the PCM. It will 'frame' due to lost data frames but it will follow your actions.

To most modelers, that is what they want, they don't care about the electroncs or software.

I have even proved this with a slow sports model in the air, both tx's next to each other. I was still able to fly the model.

For me, untill somone demonstrates a system with GREAT avantages over this, i will stick with my good old PCM.