No safety (GLOCK), one in the pipe for me with the trigger fully covered. Take you piece to the range in condition 1 with the trigger inaccessible and try to get it to fire. I could not get it to fire, and it made me quite comfortable carrying in this condition.
I have trained on different platforms with a shot timer, and it takes me a lot more than a half a second of time to draw, chamber a round successfully, acquire my sights to get on target, and fire a accurate first shot than it does to just draw and get my sights on target to squeeze off that first accurate shot. I have practiced it many times with more than one manufacturer of firearm also. The shield with and without a safety, different Glocks chambered and unchambered, Sig 239 chambered and unchambered.... Personally, I would honestly be more worried about attempting to chamber a round in a high stress environment and having a A/D with my hand near the chamber or in front of the barrel. If confronted with a situation where I found it necessary to un-holster and fire my weapon in public, I am sure that the other person would be chambered or sufficiently armed and ready to do harm without affording me the time to get ready.
I have also attended knife training courses where I have seen where people with a simunitions gun holstered in a CCW carry position had NO chance to stop someone who was adequately trained with a edged weapon in fairly close proximity. Everyone in class tried, nobody could draw and stop him. And we knew it was coming at some point. To most it was very humbling.
As stated before though, you do you and do what you can do comfortably, and maybe more importantly, PRACTICE WHATEVER THAT IS.
A good man knows his limitations...