We have a Camper and Nicholsons 38 foot CC ketch, 1974. The number one feature for us that is important is that the fully enclosed cockpit
provides great protection from the elements - we live in the Pacific Northwest
and want to sail most of the year. Let's face it, even summer can be miserable at times....
My wife has pretty bad rheumatoid arthritis, and without the protection offered by the CC design, she'd have a hard time sailing in the summer up here. Or put another way, the protection offered by the CC is a sine qua non for us. I suppose you could do that with an AC, but it's a natural for a CC.
Disadvantage of a design this old is that head
clearance is not always the best, and the berths are not well arranged. Not a good double berth - we plan to fix that though. Hard to see how a CC on a boat smaller than 38 feet could work, but I suppose a really good designer
could pull that off.