I Miller locked my rear-end on my Sonono and it was great. My 2WD could "krawl" through cracks and stuff. Didn't care what it handled like on the street but it did some major hoppin' and screechin. After one too many powerslides around corners, my driver's-side axle decided to de-spline. At least I know my fabricator can weld stuff stronger than the rest of the driveline, hehe.
If you have a stronger rear end than I do, go for it. The truck will become super-predictable and you will be able to slide all day long in it. That's another thing, it will make the truck over-steer a lot under power which I absolutely love.