I quit a long time ago using the MX-800 because of poor RF performance even with the 3.0 firmware version. I was doing and install two weeks ago with a Xantech IR system where the plasma was giving me a headache with the interference no matter where I located the sensor inside the room. Also I had to put a sensor outside to control the second zone from the pool area and the sun would hit the sensor for about 2 hours in the afternoon. So I decided to give the MX-800 another shot. The firmware version is now 3.5 and it worked like a charm. I have the base unit inside a rack in a cabinet and I can control the system from the pool area more than 50ft away.