In my experience with overmold discs, mostly MVP and Axiom, they take forever to break in. Mainly in my mids, I like to have a couple molds with one seasoned one and one more fresh, and maybe even different plastics. I'm starting to carry that trend in to my drivers. I used to not care, but as my discs break in and lose stability, and I add a newer one of the same mold, Im starting to see why people like having fewer molds. Its not something I was ever able to do when throwing MVP discs. I also noticed that regardless of the plastic, the stability seems to be the same. Not a bad thing at all, but I like having the ability to have a couple plastics that fly a bit differently. Like my Champ and DX Thunderbird. The Champ is a straight flight with a good fade. The DX is a straight flight with little fade. The only MVP disc I've ever been able to do this with is the Volt. I had a Neutron and Fission and they paired very well together.
So the overmold does have effects?