You need to use the firmware that ML is programmed for. If the ML manual says to install firmware 1.1.0 (and that version only is listed), you're taking a chance of screwing up your camera if you use anything different. I'm using ML with my t2i. I followed the instructions and installed the firmware update the ML manual instructed and everything is fine. You might also want to find out if there is a limit to how many times you can update the firmware. I recall reading something about that, i.e., that if you change it too many times the camera will stop working and you'll need to send it in to Canon.