Just curious to find out what the difference is between a "regular" shaped crank, and a "web" shaped one. And why is it better or not?

 

It is lighter because of less material, this allows for quicker and slightly higher revving engines, but at the expense of not being able to lug the engine as low and does not hold Rpms as long. Its quick on and quick off of power. Thats the reason, to get a quick acceleration and give it a slight 2 stroke feel.