I would like to see a two-second hold option on it, where you must press the button decisively before the record command is sent. As it is, users would be safer to delegate this function in the LCD region. Click to enlarge. On the other hand, if a preprogrammed code doesn't require a particular button it is left truly blank. So, after some searching I discovered that you could assign the AUX preprogrammed code number 155 to all devices before learning.
Remote speed is fantastic, always quick and nimble.
Each time you return to the Main Menu, the lower hard buttons retain all commands from the previously active device - a great feature. One engineering quirk is that the backlight flickers noticeably as signals are transmitted. This could be seen as either a good or bad thing, depending on how you look at it. If you don't need confirmation, it's a mild visual nuisance. MX-500 is the epitome of good design and reigns as the best hard buttoned remote I've so far had the pleasure of using.