The RTS 555 is better unless you are working on extremely large sites that require measuring distances over 1200 feet. The RTS 555 utilizes internal batteries that make it much simpler to set up. It utilizes Wi-Fi to communicate to the rod/data collector which is a more robust solution and eliminates wires at the rod. Finally, the 555 is built on a platform that Trimble is going forward with, while the 5600 series is finally being retired this month.