This is what I have learned about epoxy vs glass.
Epoxy is much easier to work with that glass. I still build things out of glass, like livewells and cap/patches, but if anything needs to be attached or stitched together, epoxy is the only way to go. You get a much stronger bond than with glass, especially to coring materials or old glass. Epoxy actually has a secondary/chemical bond with glass when you applying it to old glass. New glass on old glass only has a physical bond, and prep is CRITICAL. Not so much with epoxy, it will stick to old shiny glass.
I get all my stuff from
Bateau out of Vero Beach. They have a great message board, and great technical support. Delivered to my door, epoxy is about 70 bucks a gallon for their "MarineEpoxy" product. As far as exact measurements, it is a 2:1 ratio, and for small amounts, I use the pumps, and for the big amounts, graduated cups, no big deal.
I have tore a bunch of factory and after factory stuff apart, and it amazes me how easy most of it comes apart. I only had to tear some epoxy based stuff apart once, and that stuff has an incredible bond to glass and penetration into coring materials. The material the epoxy is connected to will give way before the epoxy does. Also, glass kicks in 15 min, and whatever soaks in, in that short period of time is all there is, epoxy will soak in for hours, and if you use the slow cure in cooler temps, many hours. Epoxy is waterproof, glass IS NOT. I think that is why there is so many coring failure with glass hatches.