My spindle is about 10mm behind the ball. Its good for distance riding but i lose about 30 watts maxed out sprint power which I dont care too much about anyway. I get better knee stability like that and am overall more comfortable.

The link provides 3 techniques to determine the "correct" position. all give different results which leads me to use the universal rule of bike fit, which is:

"Do what is comfortable and ignore every rule of thumb you ever here"

Seriously what is the obsession with people setting knees and feet over the spindle to the mm when they rearely ride on flat ground. the moment you go up or down hill the relationship no longer applies.