,,,the reasoning like PCP's "[Tabarly] was not a theorist but you can be sure he knows what he was talking about", with all due respect, is not very appealing to me.
Well, as Leonard da Vinci once said: "Experience is the mother of all Knowledge"
and Marchaj had some but not much in what regards sailing.
On other hand, experience, with full keelers and fin keelers was a thing that Eric Tabarly had in huge amounts: “A former officer in the French navy who is often considered the father of French yachting”
Marchaj made a notable theorist work trying to explain reality (based on 35 year old sailing boats) trough equations and mathematical calculations but let me tell you that even if static stability is a simple and forward thing, dynamic stability is a very complicated subject (the interaction of a variable sea motion with a boat and its effects on boat stability) and even today with all tank testing and mathematical computer aided models it is far from being a settled matter.
But if the science is still messing around with dynamic stability Naval Architects have been working on the model of the best boat to fast and safely cross oceans. Probably nothing as contributed as much to the knowledge of dynamic stability than the 35 years of designing small boats to solo crossing oceans, what is called the Mini class racing:
What was learned with these boats influenced bigger sailing boats, racing and cruising, in an extent that can be considered probably as the biggest influence on modern yacht design, and what was learned had all to do with dynamic stability.