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.
1984 Fast/Nicholson 345 "FastForward"
".. 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)