i used a keller for the first 9 years of my bowhunting career, and it worked great

note, it also has a setting for ground hunting, where you lock the site in for specific distances, it is a gear wheel with numbers 1-4 on it...you lock in the site for number 2, that is 20 yards, etc. the problem, you must constantly loosen the screw that holds the gear wheel in place if something is outside of that number.

i did take a nice buck and two doe on the ground with it, as well as a number of deer "up high" out to 30 yards, the difficulty on one was the angle as he was above me, and the arrow hit high and spined him, despite holding behind the "elbow" or "point" as i call it of the shoulder