My background is more in the mechanical/construction side, building power stations etc. I also spent a lot of freetime reading books and watching anything I could associated with human movement.
I cannot gasp the concept that past the point of equilibrium with the knee that a higher heel raise will be faster or more efficient given the extra time/energy required for the extra movement. If Usain was mechanical I would say he is efficent primilarily because he seems to have a more efficient exhaust/recovery cycle.