A bigger pad will generate more heat. To get a rule of thumb estimate, just think about the edge speed of the pads. A 5.5" pad running at 2000 rpm/opm is going to generate more heat than a 3" pad running at 2000 rpm/opm, just because with each revolution/orbit, the pad goes a longer distance (all this assume the same pad meterial is used for comparison). Other aspects, like how much heat the bigger pad will retain vs. the smaller pad is left out, to simplify things. The other thing that is left out is the difference between a rotary (the PE8) vs the DA (take your pick). one of the reasons that the DA is less of a dnager is because it does spread the heat generation over a wider area. whereas the rotary generates heat in just the area under the pad. This just means that you cannot allow the rotary to stop moving, or you risk burn through. If you keep it moving If so, the risk of burn through, and holograms is reduced.
If you are talking rotary (PE8) vs. rotary (PE14-2, Makita 0227/0237, Dewalt 849X), then the speeds are directly related to the diameter of the pad. If your maximum 'safe" speed of the full sized polisher is say 1500 rpm with a 6" pad, then the maximum safe speed with a 3" pad should be 3000 rpm.
Again, this is rule of thumb. The mathematical, truly accurate way is to use areas of the pads, not outer cirumference. sot the actual ratio is r^2 vs. r^2 (so it is 3(radius of the theoretical 6" pad)^3 vs. 1.5 (radius of the theoretical 5" pad)), or 9 vs. 2.25, or 4 times faster that you can operate the 3" pad vs. the 6" pad. The other thing to keep in mind is that the 3" pad needs to spin faster, as it will not cut as well if operated at the same speed as the 6" pad. This goes a long way towards explaining the mini,m 1100 rpm speed of the PE8.
