Keeping a helicopter the right way up in a swell has traditionally always been a tricky problem due to the high CofG.
I think the CofG on a 44 would be much lower as the engine is slung at the bottom (and would be about 6" above the water) whereas on a 206 or 355 the engines are up top and so the 'ability' to rock over in a mild sea state would be higher.
I'm sure Robinson must have tested this to get FAA certification for the system.
I recall Dick Sandford talking about the low CofG on the Robinson Safety Course and the ability to remain upright in quite a high sea state but I do not recall the source of the data (but I do remember a photo). SB, any better recollection of what he said?
h-we