Yes, we have. This joystick works perfectly to control our cameras. You do need a cascade cable from the joystick to the first camera if you are using rs-232. From there, you can daisy chain up to 7 cameras and have full pan, tilt and zoom control over each. Also, this unit does allow for manual focus with our cameras but not exposure control that I was able to find.
If you plan on using rs-485 from this joystick with our cameras that does not work. The joystick only has Rs-422 and not Rs-485, so I was not able to get the rs-485 connection from our cameras working with this joystick.
In short, the RM-BR300 works fine with rs-232 VISCA and our cameras but does not work in other protocols or other serial control methods.