ORIGINAL: Rodney
...When you use a pulley at the servo end, you will always pay out as much line at you retract. What determines whether or not you get slack is the way the cables are attached at the surfaces.....
Once again, you don't have to use a pulley at the servo to get "equal movement" of the cable ("pay out as much line as you retract"). A traditional servo ARM will do the same if symmetrically installed.
Kurt