"I talked to a fluids professor and she said that the rounded smooth tip would be more efficient than a cutoff tip with sharp edges."

That's not correct, for the reason that I stated. With a sharp tip (that is, looking at the tip of the wing nose-on), there is less induced drag because high-pressure air on the bottom of the wing doesn't escape to the top as easilily as with a round tip. Same thing with a simple cutoff tip (though it's not as efficient as with a sharp tip).

Increasing the angle of attack won't alter that phenomenon that much.