ocean cockpit rolling
I wouldn’t say the OC really affects layback recoveries specifically, but it does eliminate the more general problem of losing contact with your thigh braces during a roll. With the full deck across your lap you can brace your knees/thighs anywhere along your outfitting. So I find I can have more relaxed outfitting around my thighs, and still have good control when I need it. In keyhole cockpits I find that I want to have my legs in the thigh braces more often, so that I know where they are. (Probably as much a psychological issue as a practical one.)
That and…
…depending on the boat design, laybacks may be easier. Keyhole cockpits tend to be more popular on boats with low aft decks, so you get that benefit by default. One notable exception is the Nordkapp, which has a high aft deck that not only makes laybacks difficult, it makes it hard to get into and out of the ocean cockpit.