Well I'll experiment again, but I'm fairly sure that when mine is in foot mode there is no air coming our of the face vents, and a little coming out of the defrost vents.
Ok, did a little experimenting when I got off work. In foot mode, there is absolutely NO air coming out of the middle face vents. There is a little air coming out of the side/defrost face vents, and also out of the top/defrost vents.