Those tires are a DOT rated tire for hardpack use, pretty shallow tread depth on them. They also make the MOTO MTC which looks just like a Bighorn (on steroids)
which I think would be way better in the mud.
My buddy has decided to sell his, he's more of an XXC guy than XMR guy, it's at Bow Ridge Sports in Cochrane, they'll be able to give you the scoop on it.
They work very well in all conditions, I ride with the one in the videos on here, he's only broken 2 outer CV joints and I'd say it's more to do with a heavy thumb and power steering than anything else. Be warned...those things are heavy and you'll need to winch to something solid to get...