These tires are tough! They not only look tough, but can take a beating. They drive awesome on flat roads, but want to follow grooves on country roads. Nothing scary though, just jerky. It's to be expected with such a deep lug tire.
Power loss is not noticeable with the 31x10.5x15 variety. They fill a 2 inch lift perfectly. I have a 2.5 inch lift and would have gone with 32's if I had the money for rims, possible regear, and possible beafed up rear axle. 31's look perfect on factory rims.
I see no need to buy a Mud Terrain tire. This tire does everything MT's can, PLUS killer looks, traction and durability! Even if SSR's don't last as long as a Mud Terrain, I'll still take the SSR! Highly Recommended!!