"If you are starting with a tractor that already has integrated auto steer that can be controlled by the mojoRTK then the mojoRTK is pretty competitive for giving you RTK accuracy. As far as I know, the EZ-Guide 500 and other similar products can't control the auto-steer that came with your tractor"

Trimble's EZ-Guide 500s are being installed on tractors such as JD's "AutoTrac Ready" and others. The EZ-Guide 500 will control the factory installed hydraulic valve using Trimble's NavController II. This gives you the ability to utilize Trimble's RTK, and EZ-Boom from the 500 display.