The way that prop sizes was explained to me was that the pitch is like the gears in your car. Low gear you have lots of power and not much speed, and you can accelerate quickly. In high gear it will go a lot fatser, but takes a long time getting up to speed. Try taking off in a five speed auto in 4 or 5 gear. The edge is slower with the 17-6 in top speed but it has a lot more pull out of a hover. Also takes off fatser and has a better climb rate. Its like a lower gear. very simplified version but it makes sense to me anyway. Hope this helps.