I believe that in other one-design classes, when a change is made to the equipment for whatever reason, the folks with the older version are encouraged (sometimes required) to up-grade to the new version.

Short of requiring folks with the old style rudders & tillers to up-grade to the EZ-Locs, the tiller extension option would seem to be the best compromise.

This would actually give a slight tactical advantage to the newer boats, and encourage new sailors coming into the class; rather than fostering the implication that racing is the domain of the old-school sailors with the older boats, and newbies need pay big bucks to down-grade their brand-new boats if they want to join that private club. Folks with the old style rudders could then cut down their tillers and add the extensions (if they saw that as a competitive advantage), at a much lower cost.