That's a pretty impressive résumé.

First, let's talk scale.

Bigger isn't necessarily better, said Andy Ruina, a professor of robotics at Cornell University who specializes in legged locomotion.  

The bigger something is—whether animal or robot—the weaker it becomes proportional to its body weight. [See also: Designers of Giant Robot Hope for Imitators]

That's because when you increase an object's size, what you're actually doing is increasing its length, width and height. Therefore the weight increases by a power of 3 and the energy required to perform increases by a power of 4.