You got an interesting one here, i'd say perhaps continue to refine this unless you feel this is solid enough?
Here is possible a suggestion that might help those, speed running robots i think they run fast, perhaps add those limbs in, in the same way you have these, perhaps a switch blade type of a design above his head might be a cool addition to making him be able to utilize each as needed?
Hey i tried, do what is best for your design. 
i like it anyway.
