We went off-roading today for a few hours. On two occasions, the 4WD-LO setting could not move us (steep hill, loose dirt), but after engaging the rear locker, we crawled up without a slip. It was amazing. I am so glad we got the OR version with the rear locker. I guess the point here is that if you are going to off-road a lot, it might be wise to buy the OR model, versus the more popular S model.