Don't get me wrong, Bat does make decent overlays. I had his H4 Headlight kit before in spec blue. I didn't match as good as I wanted it too and it had a lot of bubbles so I took it off.
This way, the paint matches perfectly, it was cheaper and easier to do and I think it looks ten times better.
As far as how well it will hold up, it's three coats of plastic promoter, 5 coats of paint and 5 coats of clearcoat. I think it'll last.