I have a '99 Hobie 18SX. My sails are clear mylar laminated onto one side of colored Dacron sail cloth - as opposed to a pure mylar sail. I have cleaned dacron sails with dilute bleach and a soft boom before and it works well (rinse thoroughly with water afterwards and don't leave the bleach on for more than 15 minute - and test a small patch first).

I'm not sure of any ill effects using this technique on a mylar/dacron laminate. I would attack the dacron side of the sail (the non-shiny one) with the broom - the mylar is delicate and seems to delaminate very easily.

Perhaps Mr Miller can give us the official Hobie cleaning recommendation