Some food for thought for those debating and thinking they have practiced enough that racking the slide only takes a half second.
This was posted by Mas Ayoob a few months ago to someone asking about carrying their gun with no round in the chamber.
I go with the round in the chamber philosophy. The handgun is primarily a reactive weapon. NYPD SOP-9 studies indicate that it will be fired one-handed roughly half the time. The attacker may be physically on you, making it impossible to rack the slide with the other hand, and the one-handed fixes for that don't work too well in dynamic movement.
In addition to Mas's comment, when I looked at some of the NYPD SOP 9 studies for older shootings (the half shooting one handed was within the last year or so), they had one stat that jumped out. They had tracked fatal officer shootings over a 25 year period that ended in '79, and of those shootings, 1/3 of them the encounter occurred between 0'-3' and half occurred from 3-6'.
I didn't look far enough to see if there was more recent data on the fatal/surviving shooting distances from NYPD. However, if you combine these facts. That the most recent NYPD SOP Study shows that 1/2 of the officers had to shoot with one hand and that in a past study, 81% of the officers that died in shooting encounters did so at distances of less than 6 feet and you can see how carrying with an empty chamber can mean you have zero chance to defend yourself in a significant (if not majority) of situations where you would need to use a firearm to defend yourself or your family.