It really depends on the severity of the surface defect you are trying to treat, but no doubt, a rotary is superior (in skilled hands) when it comes to heavy polishing. We tend to discourage rotary use. I've seen some NASTY swirls removed with a PC though, so I would not be deterred from purchasing one. The learning curve is not incredibly high, and with practice, your results simply improve. Even for a novice, it is very safe.
Jngrbrdman,
I think you have been capable of using a rotary for a while now, but I can see your apprehension. From talking to a few friends, we here at autopia really discourage use of rotaries a little too much. We have good reason to, because the PC will yield excellent results for the novice. However, I think you are ready to jump off the deed end! These same friends, after switching to rotary power, get better results in less time. I myself am content with the PC...