I don't have a lot of experience with these, but I do think they are a viable addition to your polishing arsenal. We all know different paints react differently to different processes and products. It makes perfect sense to me that you would need a thinner pad for use on a force rotation/gear driven machine like the Mille.
These come in 3 types and 2 different sizes.
Blue (Coarse): These are used with a compound for cutting.
Fine (Yellow): These are bit more flexible than the white pads. They can be used be used both for finishing or for 1-step polishing.
Ultra Fine (Yellow): I would use these for finishing.
5" Pad = Fits 5" backing plate with 5.5" face.
6" Pad = Fits 6" backing plate, 6.5" face.
These pads are designed to be used specifically on forced rotation random orbitals (RUPES Mille).