I have an 8310 and a 7810 that evolved from running EZ steers to installing hydraulic steering valves on both.
Both are running original steercommand modules and we get along fine with both.
One plus for the new Z2 module: it allows the "turnpath" unlock function to complete turns if you want that. 

I was able to pick up the 7810 system with the valve used.
Both valves were installed under the hood so you can't tell they are on there unlike just hanging a box along the frame.