All these guestimates also need to take into account the point of sail and the wind speeds vs the different designs. I suspect there's little difference between "displacement" and "semi-displacement" designs. However a boat that can outright plane in certain conditions will have a much higher potential threshold with the right wind speed, course and sea state.
JRP's estimates for overall average speed look good.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"