Of course do testing on any new trials of mixes. Best here is experience and tests. Obviously a need for good ventilation or outdoor casting. The thing that slowly destroys the clear polyester resin binder is ultraviolet light. You can conquer that problem if the material has any halting additive to slow or stop it.
Coloring does that in many cases.
The fillers also do it. I started experimenting with this back about 1955 in the form of custom motorcycle fenders and then started mixing steel fillings with the resin for cast sculpture bases. I am in he process of casting a tombstone right now for a student that is fully alive and wants one in this material as it can also house a glass container for the ashes and then be resealed with more of the media after it was filled. It was her idea but certainly seems sensible to me not being one to want to hang around in space much once the transfer arrives. Don't get me going.