Increments...
To a racer, it is worth spending twice as much money for sails that give a 5% performance increase, because that 5% is the difference between finishing first or tenth. Sure, with the racing sails your boat will generally be faster from A to B. So the question becomes whether you are willing to pay the extra bucks for sails that give you a little performance edge but won't last as long. Some are willing, some are not. And if you ARE racing, how are the other guys set up? If their boats are really prepped out, yours had better be, too. If they are more casual in their approach, then you can compete evenly with less than state-of-the-art gear.