I'm curious as to what size (and brand for the sake of it) you guys prefer on your Griots Boss G21? I know a lot of people seem to use the 6" with the larger machine and a 5" on a smaller machine, and of course 3" for tighter spaces as well. I personally prefer a 5" backing plate on this machine as that's what I'm use to and can fit better in some places than the 6" backing plate.