Why?

the EZBoom is already controlling the rate.   The 500 already knows where you are, and tells the ezboom to turn on and off,and sets it's parameters, so it has the ability to control it. 

What's new here is being able to load a prescription into the 500 to set the rate instead of doing it manually.

The system was already replacing a Raven 440 as a rate controler, but now it will be able to replace the PF3000 that is running the 440 through it's serial port.