I'm not going to comment on CMA's explanation, but I can give you my experience with the three polishes which I use to use as my main polishes with a PC.
PG is more aggressive, both in function and substance.
Whether its because it contains bigger particles, or smaller ones that are clustered, I don't know. Based on results I'd say its the later. However, PG feels and goes on the surface extremely gritty, unlike IP. It remains gritty for a long time but breaks down enough not to leave marring...but not enough to leave a gloss (thus the name Power GLOSS, and intent)
As far as using it with a PC, PG can be used with a PC with good results. However, a PC can't break it down sufficiently, so you need to finish with IP. When I say "can't break it down sufficiently", I mean that a PC can't generate enough heat to create a result like IP (which is what PG is designed to do). That's why its recommended for rotary use. When used with a rotary you can go from PG to a LSP, or IP to LSP. With a PC you can only go from IP to a LSP.
So in conclusion, in my experience, you can use PG successfully with a PC, but not in the way its intended to finish off. It requires an intermediate step, but that's no biggy.