Greg,

You are right and you bring up a good point. For me, Pentex IS the better durability because I really put my sails through a lot of stress and strain racing them hard throughout the year. Pentex, in my scenario, will hold it's shape longer than a Dacron sail. However, for crusing and having a good time where you aren't sheeting and downhauling for everything you're worth 75% of the time, you can't beat the life of dacron. Dacron is a great material if you don't intend to frequently race hard.

Most jib sails are constructed from dacron because the stress loads are smaller and the sail usually has to flex a lot as it sweeps back and forth across the mast and rigging during tacks and jibes.