The eX - good question about locking the front. Locking the front will usually only be used to get you through relatively ugly stuff. Then you'll turn the locker off. Front lockers severely limit your turning performance because both front tires are forced to turn the exact same speed. You can turn, but your turning radius will be much larger.
My guess is that since you are considering a front locker, you are considering going off road in areas that will articulate your suspension. It is amazing how much suspension articulation will bind up your steering as well. Because of that I know a number of people that have installed hydraulic assist to their steering - in their off-road rigs. I'm guessing you won't get to that point, but the turning issues caused by the front locker combined with suspension articulation will be a surprise the first time you experience it.
I'm not bad mouthing front lockers. They are awesome to have when you need them. But they are an expensive toy that only has one use.
I can see having a locker in the rear if you're going off-road in what I'd call 'mild' areas. If I were in a job that normally took me off-road, I'd probably have a selectable rear locker and a winch on the front. The winch can be used for many other things. It can also save your butt if you're out there alone. If you get stuck with a front locker and you're alone, that's not a good feeling. (For the record, I never wheel alone)
I've used my winch to hold my truck in place on a steep hill while replacing tires, to move trees that have fallen across the trail, to put other trucks back on their wheels after rolling over, to straighten bent frame supports, pull bushes out of my front yard, and to help me get out of situations my lockers have gotten me in to.