I carry several different types of hand guns. The revolvers I carry will either be Smith n Wesson or Ruger and of course I load all chambers. When I'm carrying a semi-auto, which is most of the time, it will be a Glock. I ALWAYS carry it hot. I do this because when it comes time to defend yourself you might NOT have time to rack one in, regardless of what you may hear. Add to that the reality that you will be under a great deal of stress and you may not be thinking of just every little thing you need to do.
Regardless of whether or not your semi auto has an active safety or passive safety system your BRAIN is your most important feature. If your gun has an active manual safety and you carry with it engaged it will cost you precious nano-seconds to disengage it. If your gun has a passive safety system only then you will be fine if you can keep your finger out of the trigger guard until it's time to shoot.
These are only PART of the reasons why training, practice and experience are VITAL to anyone carrying a gun. Because no matter what kind of gun you carry or how you carry it you will be relying on your BRAIN including muscle memory in any SHTF situation.