They are. So is Mickey Thompson; if you dig into the tire specs you can see which lines from the three brands share the same general technology, although I don't doubt the manufacturing origin and materials will vary between them.
I chose the Extreme Country because it had a lighter sidewall construction (an unusual choice, I admit) while still being in the 235/85R16 form factor I wanted. Everything else was more traditional E rated overkill for my uses. Sitting at 16K miles on these now, and at worst I'm half way through their life - expect to get 35-40k miles out of them. They were a bit of a gamble, but performance-wise they've been fantastic.
Still digging my tires and plan to replace them with more of the same; I just won't let 4wheel Parts install them and screw up my wheels again. Likely going to get some tire tools and give Dynabeads a go.
Just went through a stretch of being, er, housing challenged temporarily, and had to haul a LOT of stuff around. I ended up going from 38/34 psi front/rear, to 40/36, now up to 46/40 just to handle the load. I didn't notice any undesirable changes in wear, and between the tire pressure and some good synthetic rear diff oil I've picked up 2-3 mpg, so that's where I'll stay for on road driving.