Not to further complicate things, but some fitters will tell you that knee over pedal spindle (KOPS) is really just a starting place for fore/aft position. While it's often where a fitter will start (and often end) in terms of saddle placement, personal preference comes into play as well. I like to be a bit further back behind my pedals myself. But the takeaway from this discussion is that seat posts can be used to help achieve whatever result the fitter and rider are looking for.