Plukky, we've done 200 mile days twice on our St. Francis, but they definitely were "ideal" conditions! Not something that could be sustained over a long passage
, simply because conditions don't stay that way. Sea states get to the point where going that fast puts too much stress on the boat and/or the crew gets to the point of mutiny; or, the wind
becomes too variable such that the speed drops.
In order to get consistent 200 mile days and
high load capacity will require long waterlines and big bucks.
You can certainly get good performance and good load capacity in smaller, less expensive boats.