I bought a PC and found it to be good for very, and I mean very light swirls, and forget about scratch removal. I then bought a Makita rotary buffer and you can read my review of this machine in the "Review" section.
If you couple a new rotary with
Meguiar's "Softbuff" pads at 6.5 inches you'll be set to even do small things.
Please do yourself a favor and read the review. Get a PC for applying wax, or polish. But for surface repair (even the light stuff) stick with the rotary.