I guess the big question is, after ten years and a thousand boats like this on the water, how will they hold up.
Dual energy conversion (stored diesel to electric to electric motor) is almost always less efficient than single conversion, so I'd look askance at that. Using the props as water generators might work well in a cat, but in a keelboat I'd expect that much drag on the boat is going to be a meaningful speed change--which is why most sailboats aren't using water generators on their props already. How many sailors want a prop that will give them MAXIMUM drag while under way?
Don't get me wrong, the diesel-electric bit sounds interesting. It worked well in U-boats (for different reasons) and it runs the entire railroad industry (again for different reasons) but...in a boat...an awful lot centers on how well that electric propulsion motor is going to work. Are they willing to give it a warranty comparable to a combustion engine? Or the alternator and starter in a car? Five years and 50,000 miles?