A few years ago some ignorant doofus stole a pair of MP5s from a Customs warehouse in Birmingham, Alabama, and sold them for a couple hundred to a gangbanger idiot who was seen all over town brandishing the pair like some movie pimp/bad*ss. Needless to say, the Feds went ballistic. They don't seem to mind all the Mac10 junk and sideways Glocks on the street, but they took this very seriously (plus they were embarrased to have lost them in the first place-- it was an inside job by a security guard).
Having said that, it is just my luck I will be shot by some 17 year old with a hunk of junk held sideways, and a defense lawyer will get him off as a juvenile, so I will keep my S9 cleaned, keep in practice, and pack it any time I leave the house. If you leave it at home, you will only need it once.