Back in the 60's I bought one of the Citizen-Ship two stick APT systems. It was my first proportional set. It was not a very good quality set. The servos were as slow as reed servos. The servo cases were made of a soft grade of aluminum and bent in anything other than a perfect landing. The servo output arm bearings were a slot cut into the servo case so you spent a lot of time straightening the cases. The engine control stick was a switch like those in a reed system. Engine control was not proportional, rather, it was blipped back and forth like a reed system. The radio link was good. The problems were mostly mechanical. I was finally able to buy an F&M proportional and get away from the two stick setup with elevator on the right side and aileron on the left. Having ail and elev on the same stick was lots easier to fly and the servo mechanicals were far better.
Jamesf