I realize that for the most part the OP's question has been asked and answered…so I'll just beat the horse a little more since I can't sleep at o dark in the morning.
IMO, just like anything new someone does there's a time when it's so new the person hasn't gotten the reps or developed the confidence to do the act (i.e. play golf, baseball, drive a car, etc…). But unlike learning to hit a ball and making a mistake, the consequences of having an 'accident' with a gun can be much more life changing. CH, your concerns are valid and real. A respect and appreciation of the consequences of carrying a gun is healthy. So is realizing your own limitations at this point in your experience. Too many people don't have a healthy enough respect for the act of carrying a gun, just like in your profession you could say the same thing of the dangers of fire. The danger is in doing something that might unknowingly decrease your security. IMO carrying unchamberd has those risks.
I know it's been said already but since some continue to say otherwise, OTHER THINGS ASIDE FROM YOUR FINGER CAN MAKE A WEAPON DISCHARGE!! It is true that a proper functioning modern weapon doesn't go off by itself either but it's not just those two things that can cause an ND.
With that said, if you take your finger out of the equation, the area where a discharge often times occurs is during re-holstering; either by a foreign object in your holster that gets lodged in your trigger as you re-holster or a poor holster (i.e. the mouth of the holster folds over and gets caught on your trigger during re-holstering).
A technique that is often taught to mitigate the chances of the above for DA/SA - DAO hammer fired guns (no manual safety) is to consciously put your thumb on the hammer as you re-holster. The reason is for those modern hammer fired pistol to go off, the hammer has to move. By definition these kinds of guns should be reholstered hammer down or decocked. If your thumb is on a lowered hammer, any movement is felt by your thumb before the hammer goes back and drops forward.
On striker fired weapons the technique obviously doesn't apply, so there is a risk. A revolver, DAO, and/or DA-SA guns might be your best bet until you gain the confidence/reps to comfortably carry a striker fired gun (if you ever choose too). Or maybe you train and get used to a pistol with a manual safety.
Many people discount a manual safety for variety of reasons. Thing is, most other firearms (i.e. shotguns, bolt/semi auto rifles, etc…) have them. IME, you don't hear the kind of criticisms when it comes to other commonly used weapons. The whole idea of losing fine motor skills is bull. Pulling a trigger is a fine motor skill, as is pushing your magazine release, a reload, lining up your sights, etc…It's about training. If you do something enough correctly, you'll get good at it. You might never be a Rob Latham, or an SF operator, but your familiarity of the skill becomes very ingrained. A manual safety at that point is more along the lines of a seat belt when you drive….an added layer that some people choose to do or not. As a firefighter, I'm sure you've seen the results of those that didn't wear one…I have. Yet millions of people drive every day w/o one and never get into an accident. Does that negate the effectiveness of them?
I've been in and work regularly with folks who have had to use deadly force at some point. Interestingly enough those safeties and such never got in the way. I'm not saying everyone should carry a gun with a manual safety. I am only pointing out that discounting one simply based on those common reasons is not necessarily correct. As a newer shooter it's an important distinction to decide on your own.
OK, I'll stop beating that horse now…good luck.
