JB speaks truth.
Re: Restoring my 1966 john allmand ticonderoga
If you use epoxy anywhere the you intend to re-gelcoat, it is difficult (at best) to get gel to adhere to epoxy
To use gelcoat over epoxy, you either need to find a gelcoat-compatible epoxy, or use a tie coat. This has been done, and some have reported good results, but many have reported failure. Usually easier to just go polyester, or use paint.
Epoxy has longer cure times (typically) then polyester resin which can make doing vertical surfaces more difficult and takes longer to do multiple layups so it's more expensive in both time & materials. Don't use hardware/big box store epoxy, it's more expensive by the gallon & you'll need more then one 5gal I'd suspect.
Also, fast hardener usually makes the cured epoxy more brittle, and tends to have worse amine blush.
You can do a vertical fillet w/o sagging by adding cabosil and fine chopped glass to the PB mix. I usually start with wood flour and add stuff as/if needed.