I feel as though I should contribute to this thread via a "balls" joke...

Anyways, interesting idea Takedown, but I would say it is a bit inefficient as others have said. Inefficiency can lead to more stress sometimes too, so I think your idea may, at the very least, need some tweaking. DrKnow's idea about getting that one drive shaft parallel to the chassis is a start (which I see you noticed and are considering his suggestion).

Something about two center diffs that are locked just doesn't seem like a good idea either. Maybe you should just use two spur gears to achieve the same effect but with far less rotational mass?