Yeah, I'm not really sure why or where the debate comes from... every time the answer is the same, backed by numerous different examples of physical and chemical fact... for restorations, bonding to existing cured materials of any kind, it's epoxy, no question. Will polyester and vinylester bond well enough in a 30-40mph boat and hold up? probably. depends on what you're building and what you need it to do. Yes, these hulls are built from these materials, but if the same material doesn't bond in a patch or rebuild, doesn't really matter, does it? debate is exactly that, but just be honest with yourself, if you're building a classic 15' boat that will never see more than 30mph and you wanna save a few bucks, by all means, use the cheaper alternative. If your building a performance boat of any kind (let's use an example this site can appreciate: CVX-20 Sprint, Intimidator, Scimitar, CVX-18, CVZ, etc.) with any kind of horsepower (stock or above, in any of those examples) and you are concerned about the safety of yourself and your passengers, and concerned about the longevity of your restoration, then spend the money on the epoxy. i've had to choose based on application myself, so I understand. But really, it's pretty simple. Base it on application, and base your decision on fact, not opinion. if someone "thinks" it will be ok, and it's not... then what?
