[shai]

Mott, thank you very much for the great tips. I will make sure to work together with our welders when finalizing the design.

Shir, I remember your drive train and it did worked very well.
Our center wheels are indeed lowered.
A 6WD is not necessarily less stable than an 8WD. This is because a design that places the robot's center of gravity away from the middle will result in much less swinging over the center wheel. A robot with eight wheels might do better in those terms, but we find the loss of weight and improved simplicity of a 6WD more important to us.
Our decision to use 4" wheels is based on a few reasons; one of them is to allow us to have a lower CoG.