Yes, I use one on both my LR rigs. Whatever style you choose, they are simple, light, and effective. They eliminate 1 more variable from your LR shot. Often in mountainous terrain in a hunting situation, leveling by sight can be extreemly decieving. The ACD takes the guess work out of it. A canted rifle will be responsible for shots right or left depending on direction of cant and in all case (unless youre shooting from an upside down position for you smart a$$es out there!) will also cause a lower impact. Obviously, the greater the range and the greater the cant, the more pronounced it will be.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.