@Jon: driving two wheels is actually a minor pain in the butt, mechanically speaking. You need to choose between A) drive only one of the wheels, B) force both wheels to turn at the same speed (which really sucks when one wheel is on firm ground and the other is in loose stuff), or C) add a differential ($$$ + weight).
Not that it can’t be done…the old Schwinn Town & Country upright trikes had a rear differential, and there’s plenty of (expensive, limited-production) trikes and quads with multiple drive wheels. It just adds complexity and cost.
I don’t know about the narrow gap between the front wheels on the Juggernaut…seems like it’d be tippy. My gut instinct would be for a wide-spaced design more like the Hammerhead:
I look at that thing and my Luddite circuitry energizes. Oh, I suppose it has its place, but it must weigh north of 50#, and after some point, seems it must get tiresome having to lug around all that mass, irrespective of the riding surface. Somewhat like using a Ford F-450 industrial truck for one’s commuter vehicle.