Mark,

I still haven't had time to read your post, but here is the short and sweet about the shortcomings and advantages of each system:

Measurement based system:

Pros:
- can quickly establish numbers on new platforms or modification factors

cons:
- can be cheated by designing or modifying boats within the gaps of the measurement system (see monohulls)
- cannot account for small (but sometimes significant) refinements of sailshapes, foils, canted foils / lifting foils, etc.
- caculation is complex and has to be applied by an organizing body (so no savings there over portsmouth)...probably have expenses related to measurers as well

Portsmouth:

Pros
- CAN account for minute design changes because only the boat's performance is measured
- Cannot be "cheated" around by new boat designs since ratings are based on actual performance and not hard physical design measurements.

Cons:
- rating creep can soften older platforms that are not as well maintained and typically sailed by less experience sailors leads to inaccurate ratings (an area that can be exploited).
- new or scarce designs are difficult to establish accurate numbers on which can take several years to settle out an accurate rating.


Mark - can you sum up quickly (I know, it's hard) why you think the measurement based system is MORE accurate?