No coating I know of will stop stone chips. Diy touch up can be done acceptably if you get a good match (color dependent) and fill over chip and Compound down.
I would say applying a coating without polishing would lead to an unsatisfactory result. In the sun you will likely see spiderwebing at the least. I cannot believe your getting meaningful correction and opticoat pro for around 500. Should be closer to double.
If it`s too good to be true it is. Make sure his business is approved installer. Good luck.
Bookmarks