I don't disagree with anything posted above. Except the claim that epoxy adheres to everything... clearly they've never tried to gel coat an epoxy-based repair job.
The hardness of epoxy is not a feature, it's just a characteristic. If your boat is laid up with polyester (which most are) and one section of it is repaired with epoxy, then what you have is a hull with a certain amount of flex, and a small spot with a lot less flex. It doesn't take much consideration to realize that the bond between the two is going to be compromised early and often. Also, a hard thing being squeezed around inside a not-as-hard thing is likely to pop out.. not a handy feature for the average repair.
Here's the thing.. the article quoted makes it sound like the only factor that matters is finish hardness/bond strength. But if that were the case, why wouldn't we all just build everything out of carbon fiber? After all, the weakest carbon fiber build is much stronger than the best fiberglass build.
Vinylester is excellent stuff. That's why it costs twice what polyester does. And if you are going to put a proper barrier coat between the boat and the water, then the tendency for polyester to wick water won't come into play.
Plus, if you are repairing anything more than about 5% of your boat, the savings in using polyester rather than vinylester will pay for the entire barrier coat.
Also, of course you have to wear a respirator. VOC's are present in all those chemicals. Knocking polyester because of VOC's is like knocking sports-cars because they have seatbelts. All cars require seatbelts.. and all resins require respirators.
I note that the article didn't even mention acquired epoxy allergies...
Anyway, I'm just one dude on the internet. I don't even believe myself, half the time. Call up your boat builder, and ask them what they used to lay up your hull. Ask them why. They know a ton more about boat building/fiberglassing than does some dude on the internet.
If you want me to, though, I can go on for hours about this stuff.. but I've used enough white space already