Aloha,
IMHO and recommendation to our customers I do not recommend using a PC at speed 6 with any foam pad that has a hook and loop set up.
I have witness and heard many problems using a PC at speed 6 with any foam pad. I personally suggest if you are using the PC at speed 6 then you are really using the wrong tool for the job. The PC is just that a random orbital polisher which works great at removing light swirls and polishing.
However, you need to get a high speed circular polisher like the Makita, Dewalt, or Hitachi rotary. Yes, there is a slight learning curve but you will appreciate the great results you can make in a short time. The key is to keep the pad on rotary flat on the finish, and keep it moving. Tape edges and trim. After mastering the PC, you will in no time appreciate the differences between the PC and rotary. And you will be able to use the proper equipment for the right job.
I personally use both my PC 7336 and Makita 9227 for most detailing work I do. Again, it all depends on what you are trying to achieve. And at the same time, you can save your arm and control the shakes.
With Aloha,
Ranney