Once going through security (at lga), my wallet bulged too much and they wanted me to put it in a tray--with all the confusion at the check-point, anyone could have walked off with it. Now (except for my drivers license), I put my wallet deep in my c/o before reaching the cp.
In LAS they suggest that you put all metal objects in your c/o--which I've done with no problem for some 50 trips--do other airports balk at this?
As far as having my c/o stolen (it is larger than my wallet) I stand a better chance of seeing it being removed than my wallet--no one is going to steal my c/o for the bag only--I paid $5.00 for it (and it looks just as upscale).