Is Vinyl Antifoul better over Epoxy Barrier Coat
Technically speaking, a properly formulated and properly applied epoxy barrier coat should have greater adhesion and better impermiability than the vinylester. Theoretically difference in impermiability is minute and insignificant.
Now then, when you talk about using a product named ''Bars Rust'' it was clearly intended for some other application. As a result, you have no way of knowing what its secondary bonding adhesion to fiberglass or impermiability actually is.
The other issue is the bottom paint being applied wet. That is an acceptable procedure for coal tar epoxies (used as barrier coats on cast iron keels.) Its not one that I recommend as you end up with a boat with a visibly rough textured bottom and one that as difficult to fair as the bottom paint bonds in the crevices.
Its amazing how each yard sees this whole barrier coat issue. The Interlux viylester barrier coat system is very highly regarded. The yard that works on my boat will only use WEST System epoxy below the waterline. I have been favoribly impressed with the description of the Lenox system: http://www.geocities.com/duke_of_ur1/Lenox/basbotjob.html
I guess there is no one right answer but I think what is being proposed sounds like the wrong answer if it was my boat.