^&04types- I generally use 6-6.5" pads on the rotary, and as I'm *not* a rotary-meister I appreciate anything that gives me added control or otherwise contributes to a favorable outcome. That said, my favorite backing plate for that size pad is the flexible one, I got mine from TOL. I dunno what the measurement is *supposed* to be, but I just took a tape measure to mine and it was around 5 7/8" so maybe it's the 5 3/4" one :nixweiss Whatever size it's supposed to be, it works fine with the pads, plenty of room yet not too hard to center.
FWIW I'm usually using 6.5" LC pads. Smaller ones ( e.g., 6" or some other makers " 6.5" " ) might not leave enough room for safety. Those scare-quotes around the 6.5" were intentional as some pads seem mighty small for the listed size but I can't remember which ones gave me that impression.
