I have used them with great success. I had it on a PSE and an Outback. Right now I am using a 3 pin setup on my Outback but I may go back to the pendulum. It is best to try an set your stand on as level an area as you can because they can be off shooting down (say the ground drops off) or up (bank behind you, etc). I don't know of all the possible makers of the pendulum sights but I liked the Savage sight over the Keller. I found that Keller rattled too much at the shot.
Jim