I can say from experience that there are some amateurs on Pinside who clear coat and don't know what they're doing. Many put on too many layers and/or lay it on too thick. This may look like glass for a short period but then you have clear coat lifting at out holes, posts, even screws. Also if you put too many layers on it makes the ball play slower.
I don't have experience with Kruzman but I know he has an outstanding reputation. And I know from experience that there is a broad range of quality from "pro" clear coat guys here on pinside.