I have never used one but from what other people have told me and from what I have read on the forums they are noisey.
Don't know about other brands, but get a Savage Pendulum Max and I assure you noise is not an issue. Pure silence.
Works very very well as well. I love mine.
Draw, aim, shoot. Nothing else going on in the mind...
Just make sure if you are hunting in uneven ground the shots you take stay within the parameters of the pendulum concept... 10-30' up a tree, 5-25/30ish yards out from tree, depending on the fps of your set up...