I would be skeptical of a product that claims one coat per year is enough. You can't even get a complete coverage in one coat. At least two coats are always recommended no matter what the snake oil is.
Another thing that would make me pass on this one is that it seems to be an all for one type solution. That is, it can work on the clear coat of a car/motorcycle or the gel coat of a fiberglass boat. Gel coat and clear coats are different animals, I would stick to a polymer that is specifically designed for a gel coat for best results.
Shel