Tartan I agree with you except on this:
"So a modern boat with a wide transom and the center of buoyancy more then 54% of the waterline aft and a fin keel and spade rudder will be almost imposable to make balanced under anything but the calmest conditions."
Mine does sail balanced, any wind and seas, and I have a 4.40 meter beam, a pointy bow, a spade rudder, a rectangular fin keel with torpedoe, gigantic mast, extra extra sail area and straight bow!! Yet, I can do it, as I have...
Why??? because I trim the boat to teach all the friends that keep coming over, to make them more at ease.