Don't bet on that.

The word "dramatically" blows the idea apart. It's exactly the problem we have in our hobby with sound byte ideas. One true concept gets expanded and interpreted. And winds up screwed.

It's not a good bet that a change to a 2blade is going to even increase the speed. It will if the 3blade is a really bad match to the engine/airplane, but even then, the speed difference might be so slight as to be meaningless.

I've been flying a H9 P47 alternating a good 3blade with the best 2blade I've found for the airplane. The guys watching can't tell which prop is on the airplane until I shut the engine off. I'm not sure that I'd know which is being flown if I hadn't been the one changing the props.

I've also been flying the ARF SkyBolt alternating props. Same deal with the guys, and in this airplane's testing, I'd bet good money the top speeds with the different props isn't measurable.