The problem with factory applied coatings is that if you touch the inside, or if (as in my case) the shield is shipped alone, and gets bumped and rubbed on the inside, you can't see through it until you clean it all off.
However, they work great otherwise. So, now I've got a brand new, fog free shield I can't use because the inside was bumped. Oh, well, I'll just clean it with dawn a couple of times and hope I can get the thing usable.
I'm going to look into the Cat Crap if Sven's experience is good though. My helmet is vented pretty good, and once the bike gets rolling fog isn't really a problem. The issue is when I stop at lights, or that time when I'm just getting out of my drive way.