Real life examples.
Big Ben, he weighs in a 1386 pounds, stands 16.2 hh and change, on 9" of bone, and is in hard condition.
Using the % method I'm at 23% which I think is fine for the small amount I ask him to do.
Using the calculation I am at a horrific 94. Time to find a new horse, but certainly makes you think about his ability.
Willow there, 28% by weight and scoring 96 on the scale, so a couple of points to the worse as expected.
Emmy though, 30% by weight, but 88.8% by calculation.
That makes sense to me, Emmy is more compact and on a better density and weight of bone. She is also overweight, lets say 100 pounds......
If Emmy lost her 100 pounds, she would then weigh 996, if we look at % weight carrying, then the new % would be 32% moving to the worse..
But by the calculation we would come out at 82.25, reflecting that by her losing weight she would overall be supporting less weight.
So If Emmy loses 100 and I lose 50 we will be able to ROCK IT!