In my experience, while heat is somewhat of a benefit on metallic surfaces it is NOT on non metal(plastics)! The potential of paint damage on plastic and non metal surfaces is much closer so I adjust my approach a bit with milder pads, pressure, product, machine speeds etc. I will say I'm about 90% rotary and even use it on non metal surfaces so that's where I'm coming from with my experience.
I will say that a 4" pad and a PC is sometimes perfect for plastic trim defect correction and I go that route sometimes. I still use speed 6 most of the time but alter my pressure a bit and "lighten up" to get the least aggressive but most effective correction. Soemtimes I'll back it down to 4.5 - 5 on the speed and refine the finish. The correction effort depends on the level of defects but heat should be avoided as much as possible with plastic pieces. I agree with Angelo's recommendation of IP and a white pad to start with if that's what you have but again, only you know the level of defects you need to correct.
