Surely Booth and Marstrom knew before the A class hulls were put together as a two person boat with spin that the narrower hulls would sail lower in the water to find the displacement to support the total sailing weight. That is a given. What it comes down to is a trade off between friction drag, wetted area drag, and wave making drag. The finer A class hull will sit lower in the water and have more wetted area and have more friction drag. At speed where wave drag becomes important the finer A class hull will have a lower wave drag characteristic. A wider hull of the same length will float higher in the water and have less wetted area and therefore have less friction drag. At speed this wider hull will be pushing the water further sideways to move ahead each boat length and this makes more wave drag. So what it comes down to is that in light winds you want fatter hulls with less wetted area and in strong winds you want finer hulls with less wave making drag. Everything is a compromise.
Bill