The p/c doesn't generate much heat at all, at least directed to the paint, which is why it's so safe. With the p/c (Porter Cable 7424, Meguiar's G110 for those who aren't clear) accomplishes leveling of paint through the abrasive action of both the liquid and pad used. It can do remarkable things if you know what you're doing, but virtually no damage if you don't know.

This guy, Presidential Detail, is also a member of meguiarsonline.com and on this project he made use of a Makita 9227 rotary buffer - a completely different tool - along with a Meguiar's Solo wool cutting pad and M105 Ultra Cut Compound. Honestly, about the only way to get more aggressive than that combination of machine/pad/liquid is to wet sand. This is the same approach I had to take on my Crossfire when I picked it up. It had lived on dealer lots for 2 years and was a mess, and this combination was the only way to remove all the defects in the paint. As for heat, this combination will generate a lot and can actually generate too much if you don't know what you're doing. Where the p/c can be learned in literally a matter of minutes, the rotary takes time - often a lot of time. Even so, on a modern clear coat it still isn't the heat so much as the cutting ability of the liquid and the pad that gets the work done. But this combination can offer a lot more cut.

Now if you're working on an old single stage paint, the heat can actually cause the paint to flow again, which helps to level out any defects. While there may still be a tiny little bit of this going on with a modern clear coat, it's a very small percentage of the correction process. After an aggressive rotary polishing session like the one shown in the MB forum thread you can measure how much paint was removed via use of a paint thickness gauge. With a normal p/c buffing session, the vast majority of paint thickness gauges will show no difference in film build.