My biggest concern with them is being caught with a dead battery---in the car or on the fob. I know, there is a drill to get around that but I would just as soon have a key---unless the lock freezes, I know the key will work.
My first one was on my Corvette and I don't think I have had anything since that did not use the keyless system. The MB is typical German---the fob is both. The start button has a cover over it, pull the cover off and the key ignition switch is exposed, the end of the fob is the key.
"A pessimist sees the difficulty in every opportunity, an optimist sees the opportunity in every difficulty” ---Sir Winston Churchill
"Political extremism involves two prime ingredients: an excessively simple diagnosis of the world's ills, and a conviction that there are identifiable villains back of it all." ---John W. Gardner
“You can’t go back and change the beginning, but you can start where you are and change the ending.” ---C. S. Lewis