Jake You must talk about Accuracy along with Transparency... it does not serve the debate to consider only one factor.

Accuracy assumes that their exists a perfect single number rating for a boat. Now... even if we knew that number... the fact is that the racing rules of sailing will add noise of a few percent. So...the precision of your finish time is plus or minus a few percent. Basically the tables use one decimal place and you can have two classes tie on corrected time even tho one beats the other across the line. Handicap won't resolve close finishes as well as one design. That is the nature o the game... Accuracy of any table is always debatable.

We obviously want an accurate ratings table and accept the limitations of finishing by time and not position. BECAUSE accuracy is in the eye of the beholder... we count on the national and international sanctioning bodies to declare one table is accurate and approved.

Of almost equal Value as Accuracy is Transparency... Do you know the factors used in generating the rating because it is likely that you (or someone) will disagree with the accuracy of the table for your boat or theirs. Transparency addresses HOW you get to an accurate table.

How you get to an "accurate" table of boats is one of three ways.
Accuracy is in the eye of the beholder SO...we count on the sanctioning bodies... ISAF and US Sailing to declare one or all acceptable. US Sailing declares three handicaping systems accurate. PHRF, Measurement and Portsmouth. They differ in transparency.

Portsmouth... collects data for yardstick and active one designs and generates the table. Problem is. Not enough quality data for new designs racing against the yardstick boats exist. All data have to be filtered. The races used to calculate a rating may be historical because 100 data points are used. The problem is with getting valid quality data and major corrections have been required to fix problems that were caused by bad data. One off boats get ratings (to be user friendly) that are not valid.

Measurement. A committee works out a formula based on the sailing physics, curve fits to data, etc etc. The rating table is based on the published formula applied to all boat classes and the measured parameters of a specific boat or class of boats (one design) Examples are MORC, HPR (Monohulls) SCHRS and Texel (cats.) This table is the most transparent.

PHRF... A committee works out their best judgment based on declared parameters and measured values and the observed performance on the race course.. This is a local committee which takes into account local issues like current etc.
Transparency is low because the committee meetings are private... but you can appeal your rating. PHRF tables exist for monos and big multis' PHRF tables differ a lot across the country.

I believe that SCHRS is the best solution for both Accuracy and Transparency PLUS it is sanctioned by ISAF.