In the late 70's early 80's the IOR boats mainly were masthead with big kites and small mains. There was a lot of boat underwater and small little pinched sterns. These were the boats that rolled the best. Later on in the 80's most of the boats had much bigger mains and much smaller frac kites. Less boat underwater and wider sterns. These boats rolled much less, but they still rolled! Choking the sheet down near the chainplates helped with the rolling, but you could never really completely control the tendency.
I remember one Cowes Week going downwind in a blow on a Frers 55 with the helmsman going lock to lock on the wheel for over 30 minutes before the boat wiped out in a spectacular Chinese jybe. A guy in the back of the boat nearly bit his tongue in half when the runner block came flying around and hit him in the face!