Compromise and use the three blade prop for static display only.

At the rpms our engines operate, three blade props absorb extra horsepower without producing extra thrust. Most full size aircraft that use more than two propeller blades utilizing gear reduction units to slow down the rpm of the props, where they are more efficient.

Of course, if you try a three blade prop (a good idea just for the experience) and are satisfied with the results, who am I to argue?