Judging by the number of dismastings , collisions, breakdowns and what have you, the boats suffer in the Vendee, I'm not sure how seaworthy they really are. It can be forgiven because they are race boats and racers tend to push it to the edge. On the other hand I'm not sure open 60s are a good example of how much safer larger boats are.
I was just comparing what is comparable: The same type of boat specially designed for solo sailing, one with 22ft, the other with 40ft and another with 60ft. The comparison regards only those types of boats and the relative seaworthiness between them.
We could do the same exercise comparing the relative seaworthiness of other similar typed class of boats. We can look for instance to Benetau Oceanis series and compare the blue-water ability (and safety on those conditions) of an Oceanis 31
and the one of an Oceanis 45, or go to the First series and compare the Blue water ability (and safety on those conditions) of a First 25
and a First 40.
Sailing Yachts - BENETEAU
This is so obvious that the discussion makes no sense.
Why I am persisting? Because it is dangerous to assume that for the same type of boat size has nothing to do with safety.
That is just plain wrong and assuming a boat can be handle by his crew, bigger boats with the same type are more seaworthy and safer than smaller boats.
Ignoring this can lead to overconfidence and to dangerous situations.