It says in big red letters: "CCW until XX-XX-20XX" right above your picture.
Advantages:
-Lots of times when you use a credit card, cash a check, buy alcohol, rent a car, check into a hotel, etc they check your DL. Do you want them knowing you *may* have a concealed weapon on you? What about going through security at the airport? Not that you're carrying, but get a jerk TSA agent and you might get flagged.
-When in a traffic stop in and out of state, the police will not know you may have a concealed weapon in the car (unless a MO cop looks to see why you have a ID card and finds the endorsement through MULES.) Do you want an IL cop seeing you have a CCW endorsement? Even though you're not carrying in that state, it could cause some unwanted attention. There are very long threads on whether or not you should inform the officer (not required to legally.) Make your own decision on that, but it's one more step to conceal your CCW.
-In the great state of IL, get a citation for a moving violation and the officer can take your DL as bond. You have to give them cash on the spot or pay at the county court house several weeks later to get your DL back. Same goes if you ever get your DL suspended or revoked. Your CCW is on a separate ID and hopefully not compromised.
Disadvantages:
-You have to carry a second ID.
-It an extra couple bucks to renew it (two renewals vs one.)