I don't call those draw lengths particularly short, so you are comparing a 3.7 percent change in draw length, to a 17% decrease in brace height.

Also, you don't get the same bow often in the short draw length model. It isn't going to necesarily be a bow redrawn in every proportion to simply scale down the "forgiving" bow.

If however you scaled down the bow in a forgiving way, I buy your basic proportions theory, but it would probably only justify a change of about 1/4".

I think the critical factor is how well anybody shoots. If you have a great grip and bow arm position/performance, then I think that you will probably shoot a low BH bow with little difficulty. If a person is a bit of a hack, they are looking for further problems.