I was looking at some French designs yesterday (bord a bord, bretagne) and I found many of their designs were 25% between light and loaded. Not much adjustment for cat versus mono. Alloy boats.
As cheechako noted bridgedeck strength may have plenty to do in case of a cat. I think for a mono sail boat loading her up may result in huge alterations to forces on the rigging
that may ultimately end up in failures.
I'd rather my boat were way 'too' light than a bit too heavy.