The real problem with a Glock is the "half-cock" design. The instant you chamber a round, the striker is partially cocked. The point of that design is reasonable at first glance - constant trigger pull weight. It would seem that the "safety-lever" in the middle of the trigger is the safety. Testing it (with Snap-Caps of course), one readily can see that pulling on the edge of the trigger won't set off the pistol but, touch that lever and even a light pull fires it. Holsters, especially generic tacti-cool types, are a disaster waiting to happen. As earlier in the thread, the trigger must be covered. Holstering the pistol comes with other exposures such as a t-shirt catching the trigger, as mentioned. The only protection is holstering carefully and watching while doing it. Even trained and experienced professionals can get fooled. On this site, about a year or more ago, there was an article about a police Sgt. who, while holstering his Glock, got a drawstring adjuster/lock (the drum style) from his windbreaker caught in the trigger housing. It was the perfect diameter for the trigger. Fortunately the discharge "only" gave him a burn. One needs watch carefully, not real easy in a high stress, quickly unfolding situation.
I used to carry a 1911 IWB, hammer down, and would cock it on draw. Got used to that a long time ago. But, that was the 1911A1; the newer iterations have the longer beavertail, interfering with my thumb. The manual safety looks good on paper, if one carries in a proper holster OWB. I've found that the safety can be worked to "off" while carrying IWB, though that may have something to do with my Dunlop (tire that done lopped over my belt).
So, I've migrated to a SIG. Main reason was to have consistent operation with my Summertime carry, a smaller pistol which is DAO. Now, I can have a round in the chamber, hammer down, and a heavier trigger pull on the first pull. The latter often is criticized but, it's just something to get used to. And, it's just forward of the hip bone.
Hurrah for the Bonnie Blue Flag that bears a Single Star.