I do.
Just used it, as a test, on an Ultimate, which comes 800 grit dull/matte, and on a Rush, which comes 1000 grit dull/matte. Haven't tried them yet. Once I do, I will decide then how to change them, if it is necessary.
Renew-it supposedly can take a ball to as much as 2000 grit. Where you take it depends on how much you use, how hard you press and for how long. By my estimation, I tried to take these balls to what I estimate is around 1200 grit polished.
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"We get old too fast, and too late, smart."