I love mine. It deadened what I felt was already a really quiet bow. Yes you have to serve where the STS contacts the string. I don't know anything about the double ones. Front or rear mount doesn't really matter other than what your bow is already tapped for. Besides the quieting, my groups tightened up as well, due to the arrow leaving the string at the same point. That part will probablyvary fromshooter to shooter and also with how tight your nocks fit. I am frugal, and not a gadget guy by any stretch, but I love this STS system.