The primary advantage for the pull/pull is complete and positive control throughout the entire range of movement of the rudder. Especially in the larger sized aircraft. Using control rods on only one side of the rudder provides good pull, but often a push with slop or bending of the rod attached to the rudder. That makes a knife edge loop in a larger size plane near impossible. Pull/pull also sets the stage for much faster control response.

I can't provide any pictures, since I don't have a camera. If you go to the AMA website and look up the building the Extra article, you will find excellent pics and info on setting up a pull/pull system. Remember that all the geometry in a pull/pull has to be the same at both ends of the set up