I use a Savage pendulum sight and have for years. I primarily treestand hunt. I don't ground hunt, but my pendulum is set for about 20yds on the ground. It's dead on at any angle out to about 30yds from a treestand height of about 20ft.
To me the advantage is, being like a single pin, with always the proper angle etc. The disadvantage would be, being able to shoot further on the ground. Pull up Savage Archery or Keller Bowsights for more advantages or disadvantages of pendulum sights.