Giant scale folks make an effort to make the rudder pull-pull with 4 servos ganged up for rudder. Then for control "goodness" they go to an aft mounted servo or two servos on each stabilizer half and a short pushrod to the elevator.

Why the difference? Certainly a tight pull-pull system is just as tight as a direct servo connection. Or the reverse, if direct is so good why not use it on the rudder?

Another question. Why use a pull-pull when a big diameter carbon fiber tube push rod would be rigid and let you put the servos up in the equipment bay?

Granted dual elevator servos per elevator half gives some reduncy in failure analysis.