I'm not going to try and take sides here, or get into any of the issues that have already been brought up, but an interesting thought does come to mind. If you're a staunch, 100% OC'er, there could be an upside to carrying without one in the chamber, provided you have a BUG or clip knife you can get to in a second. If people see you have a gun, they may try to jump you to get hold of it, to either steal the gun and/or rob you, and what happens if you attention level drops from high yellow to low yellow like those of us who mostly carry concealed? It's possible the gun could get grabbed from you if it's out there in the open, particularly in a OWB rig, and if that ever happened, it would be worth the price of admission to see the expression on the perp's face as he pulled the trigger and it goes klik!! about the time your bug fires or your clip knife comes in at his throat.
Unfortunately, preparing for that eventuality looks to be pretty low odds to me compared to keeping the element of surprise, particularly if your attacker is armed, and may not see the gun to begin with. Just because it's out there doesn't mean everybody, or even most people see it. When I OC'ed at the Lake Harriet Pavilion for Joel's OC picnics, only about 5% of the people noticed as far as I could tell, and you really can't count on some thug with a low IQ being that much more observant if he thinks you're a good target and comes in at you.