I understand that--but have you measured the diamond tension with a loos just to see where you're at?

My cat Ashby main is lighter and softer material (pentex, I think) compared to my Goodall sloop main. It has a larger fat top (not radically larger, though), mini battens between the top battens. It is very shapable and easy to manage. I'm honestly not sure about the relative fulness at the bottom--the sails don't seem that different to me in this respect; the outhaul and other controls seem to be able to make just about any shape I want. If you pressed me I'd say the Goodall sail is fuller at the top compared to the Ashby sail.

Overall I can't sense a difference in speed, but the cat main is easier to sail with due to the softer material and larger top.