Also Chuck,if it peels like latex after 6 months then you have a surface prep issue at the very least.

I can tell you this. I HAVE put this paint over stuff that makes it peel off-- when I was spraying test pattern with my HVLP gun before painting my door jambs, I sprayed over an area that was painted with the rustoleum clear coat in a rattle can. That paint (over the clear coat) I can peel off pretty easily, it does not seem to adhere to that.

Whatever you painted over was not well prepared for adhesion. Though I have stated that the paint is soft/scratchable for some time, I do experience that it gets harder and harder with time, and would never be EASY to scratch off after a month or 2, much less 6 months. Surface prep problem.