Mark,

Rating system is necessary for local fleet to race together.

First, rating is only an approximation, what about difference between light wind and breeze ?
Considering only potential power is not avalaible when some boat are overpowered and some other not.
Powerful cats paid twice when breeze: first time on the water (not too easy to stay on this furious horse), second time in the computer when calculating the "corrected" time.

A detail, the same rating when the end of race is downwind or upwind ? oooops
Who care about one leg upwind ?

On long race distance rating is a joke.
Last year Nacra 20 at the Corsaire, were more than half an hour in front of other C1 (Viper etc...).
How to compare seriously when you do not have the same wind ?

A necessary bad .... is a good description.

For your info, the SCHRS never test the formula on real world.
It was only calculation based on measurable dimension of boat.
A necessary bad, but not so bad system, with two major difficulties:

-the weight crew, 75 kg per crew, is for calculation only.
That means, by the way, that only F18 were correct with the formula.
And 10 kg on the boat means approximatively 1% in the formula so 36 second an hour, team at 120 kg gain 1 minutes 48 seconds on an hour race, what about sport ?

-no real control system. Who's checking ?
Have you ever seen a protest based on false rating or modified boat.
Indeed there is no big deal if rating is for local races. No high sport interest.

Second, the change that included performance in the rating is a very strange thing.
It is now an handicap system. The same system for the horse races to increase hazard in the result.
Here the equality is scheduled for the end of the race.

This kind of rating will be mathematically perfect (not philosophy) when all the boats cross the finish at the same corrected time.
Very strange race indeed.

The french MNA postponed the application of this kind of system 2 years ago.
French sailors prefer the old "only calculation on measurable dimension" SCHRS and struggled against this kind of system (not only at the bar ;-), because the figures where not enough serious nor deep and the philosophy is not fully sportmanship.
The F18 fleet is active and strong so let's handicap F18 people !
That is a not a good spirit for cat developpment.

Now the SCHRS is the place of the battle.
Not Plato or Socrates, more Staline versus Churchill here.

When you're sailing on a F18, that does not mean you're sailing like Besson, Backès, Hermskeerk, Visser, Begeman.
And with this performance system there is part of top european F18 sailors in your rating.

Cherry on the cake your rating will change every year at the "light of experience".

SCHRS is necessary for local race (and orphans cats in main event).
But the formula of the rating need to be a "cristal clear" one.