I haven't done it with a foam finishing pad, but I have with one of the Surburf microfinger finishing pads.
The FMJ actually spread very well, and went further than it would've by hand. I applied it in an "X" pattern over the pad, spread it a bit, and applied at a low speed.
The reason I don't use the PC to apply LSPs often is because it's just a pain in the *** to reach certain places on the car, so it ends up being quicker to go by hand. No difference in looks, so choosing the faster route is more efficient.