Pedal foot position - balls or arches I notice that when I pedal that I mostly seat the pedal in the arches of my foot naturally. I also notice that the cycling shoes tend to seat the cleats in the balls of the foot area, as do other cyclists. I was curious about the justification or pro/cons of either. When I try to pedal in the balls of the foot location I find it a bit better to be aggressively pedaling, but my foot slowly drifts back to the arches position. I ride flat pedals only.
The ball of the foot gives a large, strong, stable area to use on the pedal, and gives you a nice lever to use your muscles effectively. Conversely, the arch of your foot is soft, elastic and not stable. 

Picture your foot as you walk slowly barefoot, you push down hard on the ground with the ball of your foot, and the arch acts as a big rubber band to help spring the heel up and launch you forwards. You can walk or run solely (ahem) on the balls of your feet, without using your heel, thanks to this elasticity. 

So what... Well, the ball of the foot is a strong, stable fulcrum for your foot while the arch is not, which is why you've noticed the ball is a better location for "aggressively pedalling" i.e. better power transfer. You probably also recruit lower leg muscles more naturally and powerfully using the ball.

I don't know if there is risk to you using the arches on the pedals (maybe someone else does) but there are definitely benefits in learning to use the balls of the feet. You'll use your joints and muscles more naturally, be more powerful for the effort you put in and look super cool too.