I dont agree about the properties of Poly versus Epoxy, generally speaking that is...
Polyester is a bit softer (good or bad ?), but also MORE brittle than epoxy (besides being weaker)
And many production boards are TOO light often, so the brands are making boards a bit stronger and heavier in some cases...
But very rider dependant of course.
Some like to use a huge number of boards, and have them super light (thin glassed) - others want to be sure the boards will hold a while, so they dont get a bad session on the best waveday the whole year, if they dont have spare boards that very day.
Strapped you ride a lot harder (most do), and tougher on your board.
But strapless if you jump high, you can REALLY break any board, and much tougher on your board anytime, than strapped
So very individual, and depending on your ride style and waves in so many ways