If I ever buy Pentex (or any other taffeta-covered laminate) I will get the gray-colored fabric to hide the mildew. Even though they use mildewcides in the newer glues, it is a losing battle.

My newest set of sails is exposed laminate (except for the trim and UV cover) for the mildew reason. The sailmaker says the laminate has UV inhibitors, which I figure is as good as mildew inhibitors (grin).

In general I figure you should get 7-8 years from a suit of sails (before they need re-stitching at the very least). Anything longer and you're ahead of the game.