Yes they are each programmed to one of the channels 1 to 16 and respond only to that channel. Its the same as an SBus servo. Essentially the addressing is done by the decoder and not inside the servo as an SBus servo would do. BTW I believe the culprit in my scenario above is the Savox servos. I replaced the rudder with a Futaba servo and everything works every time. Not wanting to re-engineer this all, I am ordering Futaba servos at double the cost of course!
Len