Since I can't seem to get anything done with larger pads (even KMBing with
M105/M205

), I use speeds 4.5-5 with my 3.5-4" pads. It just seems to work better for me at the slightly lower speed, more stable with the little pads I'm using (might be different with othe 4" pads).
I've turned it down to 4 for final passes with M205, dunno if it really mattered though.