Hiktec and Futaba
As AM said, your present system and Hitek are completely compatable except (to plug Futaba servos into the Hitek, you must remove the little index key from the Futaba connectors). Also, the Hitek servos will move in the oposite direction of the Futaba, just flip the reversing switch on your transmitter to use the interchanged servo if already set up for it, i.e. to replace a servo already set up with the other brand, you need to reverse the throw at the transmitter.