Moving a larger mass of air at a slower speed is usually more efficient. Some of the bigger resistive forces are bearing friction and wind sheer. Both of these go up with blade velocity. Two good examples: wind turbines and the 'open rotor' turbine engine, which may make a comeback.

Wind turbines use the largest blades they can to minimize frictional losses (other reasons too).

The open rotor turbine is a very efficient engine. The blades are exposed, rather than inside a duct. There is a huge boost in efficiency because the sheer forces at the blade tips are significantly reduced in open air. In layman's terms, this is because of the 'no slip' rule, where the air touching the inside of the duct is not moving, and the air touching the blade tip is moving at the same speed as the blade tip. The smaller space you have between the duct and the blade, the larger the sheer forces due to viscosity. Open rotor eliminates that boundary layer.

With any design, you have to manage tip speed as airfoil effectiveness changes drastically when the air flow gets close to sonic speeds (air starts to compress).

Another thing I don't think I've seen mentioned is the size of the prop stream with respect to the airplane. Obviously the goal is to keep air moving over the wings and stabs. With a larger diameter prop, the stabs have a better chance of being bathed in the prop stream. This allows the control surfaces to be effective in more adverse conditions than with a smaller prop stream. I would imagine this is important to full-scale design, and if so, it would make sense that a larger diameter prop is desirable. If power is limited, you would have to sacrifice the third blade to get a larger diameter prop.

Just because the 3-blade of equal diameter 'needs more power', it doesn't mean less efficient. It means the engine is not sized to accelerate and maintain propeller RPM in varying flight conditions for that prop. There is a trade of efficiency for overall performance (instantaneous thrust, acceleration, etc).