For me the main difference is that 4s have more torque at low and mid RPM when you actually need it because at top RPM 2 and 4s will have almost the same (making the right comparison obviously), I run a 14x4W APC on a Magnum 91fs on my Diabolic and works like a dream great engine prop combination and this engine it's lighter than a OS 61 2 stroke that I still have on the box, but I'm using a larger prop easily , I do waterfalls almost at the same height, throttle response? not an issue it's as good as my YS120. I think it all comes to preferences and what really makes you happier depending on your abilities to set up the engines. P.D. I only use 20/20 fuel on four strokes.