6mm or 1/4" SK90 dyneema, manufacture of your choice. No reason to go to the heat set stuff, and no need to buy up $$$ to the older set of line diameter standards. If you prefer greater durability, any good dyneema cored double braid is probably sufficient, and will avoid some of the snags and chaffing that will be experienced with a single braid. Most of the high techs you'll need to continue with the practice of bumping the main halyard after tuning up for the start of a race day, or between races. Mostly it's just pulling the slack off your horn cleat once you get on the main sheet and vang a bit.