The "modern" road pedal as invented by Look was fashioned after ski bindings. Due to this they did not have float. Look came up with the arc system to allow for float and the guy that started Look left and started Time pedals. Time made the leap to biomechanical fit and float.
So if you are comparing preLook pedals to 1980s Look Pedals. The only difference is what the pedals do to your knees.
Here is a good
link
Stack height only comes into play, IMHO, when in TTs, Crits, or on the track.