ORIGINAL: forestroke
overall the 4-strokes of the same displacement will turn a prop larger than a 2-stroke at the same RPM. yes 2-strokes can turn a tiny prop at huge rpms but for all around tractability, a 4-stroke will kick the pants off a 2-stroke. I would assume that's why most 3D and F3A prefer 4-strokes over 2-strokes. just my two cents.
The only 1.40 or 1.60 size four strokes that can turn the same diameter prop at the same rpm as OS 1.40 or 1.60 pattern two strokes are the supercharged YS engines. When you get to the larger sizes, two strokes are generally tuned for low rpm (7000-9000rpm) power, especially the ones designed for F3A.
Electric power is being used in about 1/3 of the F3A planes overall and by about 1/2 of the world's top ten F3A pilots the last I have heard.
Also, most two strokes are quite happy with low nitro fuel, not that four strokes can't be built for low or zero nitro.