I used to carry with a safety and grew up using them--all of them, as on a 1911 with a grip safety as well as the lever. If one safety is useful, why not add another? Or two? Or three? At what point do you NOT need another safety?

I had a wonderful Browning Hi Power with a short, light, single stage trigger. I needed the safety on that gun because I carried it.

Eventually I transitioned my carry guns to Double Action Only triggers and went without a safety--like a revolver. But I kept lightening and shortening those trigger strokes to make them quicker and more accurate. Those triggers were no longer really a "safety", yet I never had an accidental or negligent discharge. I realized relying on a mechanical device for safety in concealed carry, with a good form fitting holster protecting the gun and trigger and modern design was unnecessary.

With a two stage trigger on a modern striker fired pistol, I realized the gun would not go off accidentally, only if the trigger safety was deactivated AND the trigger was pulled. That has been enough for me.

I do not want another unnecessary mechanical device on my self defense pistol that could interfere with the trigger action, break, unexpectedly stop me from shooting, or require additional steps to manipulate. For me, having a safety means a loss of confidence in the gun rather than an increase in safety.

As I am sure will be said, my brain and its training are my safeties, and step #1 is to keep your booger hooker off the trigger until it's time to shoot. Then shoot.

If you aren't yet confident in your training and discipline to be able to do that, or you carry in ways (like cheap holsters, or no holster) that do not fully protect the trigger, don't use a safety--use multiple safeties. Buy an Xd.