: I am wondering if there are compatibility issues with using: Epoxy resin atop
: poly resin?

: Poly resin atop epoxy resin?

: Is one a no-no and one OK?

According to the Raka manual:
"Epoxy resin products not only have a greater bonding strength, but also will bond to a greater number of different materials, including cured polyester resins. It’s for these reasons epoxy is used for so many boat repairs."

However, you need to use medium sandpaper on the underlying material to rough it up for the epoxy to adhere to. Also, be aware that the Raka tests were probably done in Florida where the temperature does not get to extremes.