Passions run high about this subject for some reason. However, there is no reputable source that I know of that shows a 3 bladed prop as draggy or less efficient.

I'm not sure about the tips being that big of a factor when the plane is moving forward. Yes, there are vortices but they are gone in an instant. They aren't ingested back into the prop.

Actually, depending on your definition of efficient, but model props can hit between 90-95% efficiency. One thing to consider is that the higher volume of air being pulled into the prop disk is generally a higher efficiency.

The 3 bladed and 4 bladed props will generally be smoother running. You will have better braking action with them over a 2 bladed prop which is good on landing and downlines.