I fall squarely in the "one in the chamber" camp now. All the stats I've ever seen indicate that many civilian defensive gun usages occur in low light, close range, and involve multiple assailants. As has been mentioned, if a bad guy is within about 7 yards of you, you have just enough time to draw and get the first shot (not necessarily a controlled pair) into him once you react. That's a time that also requires some training and practice.
If you need to chamber a round then the draw stroke is going to be substantially slower -- even if you know you need to do it and instinctively rack the slide it's going to add a half second or more. If you point in, press the trigger, and get a click (surprisingly, a louder noise than a "bang!" in a fight...), assess what is happening, tap/rack/press to fix the self-induced type-1 malfunction, it is going to probably double that 1.5 second best-case reaction time. Against multiple assailants in low light conditions at close range, three potatoes is a long time.
However, I can sympathize with those who are uncomfortable as it took me awhile to get to carrying with a loaded chamber all the time. The biggest issue I faced for awhile was having to frequently travel inside a victim disarmament zone (aka gun free zone). Firearms were allowed but had to be unloaded in a cased container. In this scenario I often opted to carry in condition 3 (no round in the chamber) because I had to clear the firearm inside the car and secure it, discreetly, in bulky winter clothing (I wasn't in the southeast). It was a lot easier to just eject the mag and press check to ensure the firearm was empty than to have to also eject a chambered round (which would inevitably fall below the floormats and be lost forever). I felt that the risk of a negligent discharge while handling a condition 1 firearm in the car in cramped quarters was too high and opted for no round in the chamber to simplify clearing.
Before that, when I was an extremely new shooter and lacked sufficient training, I was also uncomfortable a round in the chamber. That was simply rectified with training.
Brasilian -- I simply don't remove my sidearm from the holster unless I need to or unless I have a safe backstop and plan on clearing and securing it. I've had friends ask to see my sidearm out of curiosity and I just politely decline or defer until we're in an appropriate place with a safe backstop (like the range). I figure there is a zero percent chance of a negligent discharge if the handgun stays in the holster. As soon as it comes out the probability of a ND becomes something higher than zero, even for someone with firearms handling training. Why take the chance?
PCShogun -- Proper equipment helps a ton. I have a CZ as well. It is a fun range gun. Its a marginal to barely adequate combat handgun, in my opinion. I don't like carrying it in condition 0 (round chambered, hammer cocked, no manual safety) with the light double action trigger. I am also really concerned about the lack of a decocker and do not like manually decocking that firearm. The only time I personally manually decock a loaded firearm is with a safe backstop (like at the range, or at home against a backstop I know is safe). Don't get me wrong, I like my CZ, but it is not really a substitute for a proper combat handgun like a quality DA revolver, a modern polymer handgun (glock, M&P, etc), or a 1911. I know CZs are cheap, but for around the same price you can also get old Ruger Security Six revolvers and used police glock trade-ins. Just my opinion, but I think for a carry guy it is important to be confident in your rig.
I'd also agree that a proper holster (that properly covers the trigger guard!) is key for safely and confidently carrying in condition 1.
Now the only time I keep some firearms in condition 3 is when stored for "near immediate" action in the house not on my person (say, in the nightstand). I figure I have more time to react in the house. I also figure that if I am not awake enough to rack the slide, I am not awake enough to positively identify my target and what is behind it. Finally, in a house fire, ammo cooking off is pretty harmless if it is loose, in a box, or in a mag. If a round is chambered, however, and it cooks off, then it is going to send that bullet down the barrel and who knows where it will go?