I think Jake's question can only be accurately answered in terms of technological developments that have taken place over time in specific classes, and by asking how those developments have affected those classes of boats, for better or worse.

The two classes that have evolved over a long period of time are the A-Class cats over more than 45 years, and the Tornado for more than 35 years.

List all the changes that have been made in design, construction, rigging, sails, and somehow determine whether, and how much, these changes have actually improved that particular class in terms of performance.

The unknown factors in this assessment are the knowledge, skills and ability of the sailors and the sailing techniques now being used, as compared to 30 years ago.

I guess the only way to really determine how much technology has improved a given class of sailboats is to have a regatta that brings together boats of many different ages and manufacturers throughout that class' history, sail them as they were rigged at the time, and have all the current hotshots in that class race them round-robin for a week and take copious notes during the event.

And, even if the modern boats are clearly superior, you still would not know for sure what development made the biggest difference. Unless you took another week and started switching rigs around, putting old rigs on new boats and new rigs on old boats, and taking even more copious notes.

It could be a very interesting event.

P.S. In the Sunfish Class it would be a no-brainer. It took years for them to get approval for their new and improved daggerboard, but it has made a huge difference in the performance of the boat. And the difference is readily apparent because it is such a strong one-design class. Technological improvements in catamarans are not as individually apparent because there are so many changes going on these days, in every aspect of the boats, and there are so many different classes of boats, so it is hard to compare and hard to determine what really works and what doesn't.