I have the Pro Plus and just use the foam plugs that come with it. The only reason to get custom molds is to not have to buy more of the foam plugs. I can't imagine it any quieter than the foam plugs. I'd be scared of losing the custom molds. Sometimes I lose the foam plugs and luckily I have plenty more to get.

The flex looks awful and very flimsy. I'm sat in both seats with the Pro Plus and have no issues with the mic being on the wrong side.