I will be ready to do my end pours in the next few days and since I'm all out of epoxy resin from the glassing, I am tempted to use polyester with microballoons for my end pour. What I'm interested in is any scientific reason why I should not use the cheaper polyester for this application since it is about 1/3 the cost. I am concerned with excessive heat during the cure (of course epoxy can do that also) and possible bonding issues between the poly and epoxy.