On push-rod setups the servo mount has to deal with bidirectional loading; pull-pull implementations involve unidirectional loads.

Pragmatically, pull-pull systems are easier to implement because getting the cable length right is nothing more than pulling out the slack and locking the cable, whereas push-rod systems require fitting the link precisely. Providing for adjustment is the same in both systems, so that part does not factor with respect to implementation.

Push-rod systems are heavier, so if a few extra grams are of concern pull-pull would be the preferred method.