[RidgeRunner]

Not this time. Re-read. These are my observations.
You assumed mid 50's was the top-end with the larger pitch prop.

Speed prop 23P Tempest Plus does go faster, best I have seen is 63 MPH last February on the Suwannee. The best speed was obtained Boat Light, trimmed to the moon and some trim tab, motor turning 5800 on the limiter, down stream, 78 degrees, humidity 75%. Tons of propslip but it gets the bow way up. Same prop with 4 or five people in 90 degree weather and 95% humidity will only run 54 mph and the motor will only turn approx 5500 RPM trimmed to the max. Slightly too much prop for fishing load or skiing.

The 21 Lightning (Mirage copy) has huge round ears with lots of bite, and is slower on the top end I think it was 58mph (light load, trimmed proper and on the limiter). Summer prop because the 95 plus degree days hurts the performance on this EFI 250 compared to the cool winter months when it runs best. The smaller pitch prop carries the load of four or five people with less strain while allowing the motor to turn more RPM at WOT . Economy is better because the motor isn't being lugged around at every RPM range.

In theory you are right that higher pitch props add speed but only if you powerplant has the balls to turn the prop. The 25P Tempest on my shelf was no faster that the 23P because the motor could not achieve the necessary rpm to make that a reality. Fuel economy sucked worse than normal but it would cruise 40 at 4000 rpm and 50 at 5000 rpm