Ahh the old 2 vs. 4 argument. Pound foir pound a comparable 2 stroke will spin the same prop faster, no doubt. But 3D is mostly flown at low to mid throttle and requires a LOT of small power changes. In that situation torque is what you want, not horsepower and the 4 stroke is the torque king. Anyone that has had the chance to fly any given 3D plane on a 2 stroke and then switched over to a 4 stroke instantly notices the difference and prefers the 4 stroke.

The one thing I have noted about these 2 differnt types of engines is that you can get away with just about any prop on a 2 stroke as the performance difference from prop to prop doesn't seem to vary a great deal. The 4 stroke on the other hand is a completely different animal and needs to be propped correctly for the weight of the plane and fuel type being used. In most of the cases where guys are bad mouthing four strokes that I have seen they have failed to try a range of props out to determine which one is THE prop for their particular plane. When you find the right one you know it because the performance difference is that dramatic, I usually try an average of 4-5 different props before I settle on the one that works best.