I think the important thing is to have the same trigger pull and action style. So, for you, multiple Glocks would be perfect.
I think there is some validity to this, though I don't strictly adhere to it. I like carrying 1911s in a belt holster. For a pocket gun, my favorite has ben a Sig P238 (it used to be a Colt Mustang). Both have pretty much the same manual of arms.
I will carry a revolver or double action semi-auto without a safety (my recent Kahr CM9). It won't hurt if I swipe down on a non-existent safety and the gun still goes boom when the trigger is pulled. However, you have to be careful about carrying semi-autos where the safeties differ;i.e., down is fire on one and safe on another.