I think that is a nightmare waiting to happen off road.
They bring there own set of disadvantages but I wouldn't say nightmare.
High cost for us mere mortals, they have no adjustability and there are some unusual handling characteristics.
For adjustability you can't change the inflation pressure so your kind of stuck with what you got.
Not having multiple tread patterns to pick from its kind of a compromise for mud traction or sand flotation.
This is more a lack of choices issue, not a technolagy specific issue.
For the riding at TWRA that I have seen I doubt the mud would be an issue.
I tend to find a way around the mud if possible.
Not looking for the deepest mud hole to prove my manhood.
And the avalible tread pattern is not claiming to be for mud bogging.
That said, if mud dose get packed in to the spokes most of it will be ejected fairly quickly.
The huge advantage is no flat tires.
For an application like a zero turn this is a perfect solution.
I mow with an ATV and a tow behind mower, this would work well on my mowing ATV.
I have an ATV for each family member and the occasional trail ride with the mover tow-er would be fine.
(The mower and that one ATV have goo in the tires so I don't need to mess with flat tires, I hate the stuff but for this one application...)
For my SxS I'm too dependant on adjusting the tire pressures to keep up with the guys I ride with.
And I have paid the price - running 6psi for traction on rocks I picked up a pinch flat (slow leak) last winter doing the Primroy V-notch.
It would be interesting to see how the Tweel would do on that run.
If I win the lotto we should try it.