My Prediction for the F-18 class.
The F-18 class is a great idea and it will take off in the US.
The class will build for a few years with most of the sailors buying Hobie Tigers because they will also be able to sail it at one-design events.
In a few years, just as the F-18 class starts to reach critical mass, some builder will come out with a faster boat under the rule.
At this point the Tiger guys, at least half the fleet, will stop going to F-18 events because their boats are inferior. The Tigers will start sailing one design and the F-18 fleet will die.
If you would like to see a different future now is the time to start thinking about it.
Sorry I don't have a simple solution to the problem.