Grab every traction aid you can. A single diff lock may not be quite as capable as a part-time 4wd system, but it's a hell of a lot better than an open diff.
Amen to that.
I have a 2016 F150 4x4 with the factory difflock. Not long ago I was traveling down a remote two-track when i came upon a tall berm of sand/gravel that had been deposited (washed down) diagonally across the road from the nearby mountainside. I eased across it but soon found myself with one front tire and the opposite side rear tire just about hanging in the air and forward progress stopped. Engaging the rear locker was all it took to get over the berm.
Oke, and pricewise, what would a difflock add on value?