There are amazing differences across the spectrum of sailcloth being used today. Strictly racing sails are one thing, with the carbon and kevlar laminates - they're like sheet metal. The wind changes, but there's no change in shape. My sails are straight dacron - the main and 135% jib at about 6 or 7 oz, while the chicken jib (70% hoist, 70% LP) is 11.5 oz - roll that sail up and there's not a wrinkle in it! I've also got a racing jib that seems mostly dacron but has a black scrim laminated to it. Spent a week on the schooner Mary Day a few years back. Her sails are also dacron, but of a color like traditional canvas and of very soft hand making them easy to flake on top of the booms.
Makes me really appreciate the talents of a good sailmaker. Seems almost a mix of science and art - with perhaps a bit of snake oil salesman mixed in.