I might ave quite a different 'approach' to the question.
It is not as much a question of a 'Blue water boat' as a 'Blue water captain'.
The VO 70 may hardly be classified as 'Blue water boats' - but they do with 'Blue water captains and crew'.
To many the Hallberg Rassey boats are conciddered on of the best 'Blue water' boats - but with a 'monkey' as captain?
Blue water sailing is a question of balance between nature and boat/crew where the odds are a bit more serious than coastal cruising. Then comes the paradox of it: Most accidents with blue water sailors happends when approaching land/anchorages or in coastal sailing.