I have the 6" backing pad that I bought when I first got my PC and am satisfied with it thus far. I have been using the LC 6" pads, but it is time for new pads. What pads will work with the existing back up pad or is it necessary to buy one of the flexible back ups to broaden my selection of which pads to buy? I have looked at a lot of the pads you people have been praising, I just do not know if they will work with my existing back up ??