Unless you are going into large scale production I can't see it being worthwhile.

Polyester virtually sticks to nothing and will be easy. I have no experience of vinyl ester but it shares many properties with epoxy. From experiences at work years ago, epoxy released well from cold moulds as long as the surface finish was near perfect. WE had need to hot mould some epoxy items and these were a real pain to release especially on new moulds. In desperation we heated some of the moulds to blueing temperature and the oxide formed helped considerably.