I thought it was pretty simple and I'm getting confused about how a stretchy sail can be an advantage. Dacron is less expensive than the laminates and as things go...you get what you pay for. Dacron will not maintain it's shape as long. The laminates utilize the stiffer and stronger scrim materials (pentex, kevlar, carbon fiber, etc.) so that they will maintain shape better and longer.

On our cats, why do you want a stretchy sail? If it's blowing hard and I'm trying to flatten/depower my sails I would think the last thing I want is for the sail to stretch and become fuller (and/or loose shape).

Jibs, however, go through a lot of flexing and bending crossing the mast and all the hardware up top during tacks and gybes. Laminate sails are not good at this constant flexing but Dacron is. Because of that we see a lot of Dacron jibs.