Steve-
I used it since I bought the Klasse and it came with the kit.
First - I wet my applicators with it (viper MF applicators), enough to dampen, and threw on my SG.
When it came time to buff off the SG - it was difficult in a few (not many) places. I picked up a MF towel with just a spritz of the Sonus, and it came off like a charm.
Since then, I've QD'd twice (once thanks to some damn %!&%! birds). This stuff works pretty well.
Dunno if I'd keep buying it, since it's pretty pricey. But it definitely worked well, and helped remove the SG when I needed it gone.