Alan, Thank you for your reply & input.In the sage words of Indiana Jones, "It's not the years, its the mileage." If you sail/race a lot (say weekly, all season) your race sail will break down faster
than it will if you sail/race less. Sun and wind (not water) are the major risk factors. I get about three seasons out of a $350+ class legal race sail, and I know it is time time to get a new one when the boat just feels, well, slow, which is usually in the third season. The all white, Class legal sail is very well made but not that much better than the far less expensive Intensity race cut sail. Some people use an Intensity for informal club racing and practice and save the Class legal sail for Class sanctioned regattas.
Alan,As sails age, the resin that is impregnated into the sailcloth, breaks down, the cloth looks and feels softer and the max draft tends to move aft. The leach may also loosen up a little. It won't point as high and off the wind it lacks the "punch" of a newer sail. You will feel the difference more than see it.