We, too, got the color coded stickers, but so far haven't bothered to try and program the keys - partially because of what I read on here!! Doesn't seem to be worth the hassle. My wife is the primary driver of the X, so I programmed her settings into seat button one, and I programmed mine into button three. Whenever I'm lucky enough to get to drive, I just open the door and hit button three - no problem. I have found, however, that one hit of the button will adjust seat and mirrors to my settings, but only if the driver's door is still open. If I squeeze into the car when it's set for my wife and hit button three, I need to hold it down until everything adjusts for me. Not sure if this is the way it's supposed to work, but that's the way it goes. Sound German logic, I guess.
PS - I had some issues with my mirrors as well, not always adjusting to my settings, not always dropping in reverse, or not fully coming back up. Hasn't happened in a while, though - things seem to be good now at 8,500 miles.
'15 328i GT, Midnight Blue//Black Dakota
'13 MINI JCW
'07 X3, Platinum Beige//Tobacco/Black
'92 318is, Coral Red//Black
'78 316 Euro Spec (eventually swapped in a 2.0l)