I was taught:
Less blades makes prop more efficient regarding "screw-through" water.
Also taught, in trade off:
The more blades of a well tuned prop then the less chance for vibration
In addition:
If there were a way to correctly balance a one bladed prop that would be the most efficient.
So:
Three blade props offer best of both worlds regarding screw-through efficiency and reduced chance for vibration.
And:
I've always wondered, seeing as [evidently] less blades = most efficiency... why IB, direct drive pleasure cruisers don't employ two bladed props. I'm sure with today's technology two blade props can be tuned to the finest of tolerances.
Therefore:
Currently, I'm sticking with my twin three bladers. Good push and no vibration.