My view is that this rule is counterproductive and I believe regularly broken. It is a big disincentive against buying sails from an unknown source. Buy a set of dud sails and you are stuck with them for a year, by which time you are so fed up you have probably switched to another class. It stops new sail makers coming in and stunts the development of the class. Playing with sails is after all what many of us like to do.
Take the case of the keen club sailor (at Parkstone) he can sail 3 times a week. By the time the championship comes his sails are tired out, yet a less active sailor can turn up with barely used sails. Is this fair to the keen stalwarts of the class.
Yes some sailors will buy more sails if the rule is changed (instead of 2 boats like me) but this actually helps the older boats or less well-off sailors as second hand kit will percolate its way down the fleets.
When it comes to an arms race surely more sails are a lot cheaper than more boats!!!!
I also believe that if we open up the sail rule more people will come into the class as it will be more vibrant.