What's the average poundage of a sao? What makes carrying a 1911 with a 3 pound trigger, cocked and unlocked compared to a Glock with a 3 pound trigger any different? (I don't carry a true 1911 [unless you consider a p238 a real 1911], what's their common trigger pull? )
My understanding is that it has more to do with the length of pull than the actual weight of the trigger. On a DA/SA, a DAO, or a Glock, there is some take-up, and then a length of tensioned pull before the break. On a 1911 or similar SAO pistol, there is only a short pull (roughly 1/2" on a Glock, as little as 1/10" on a tuned 1911 apparently). This is why pocket carry of single actions is generally discouraged as well. Because you know exactly when the trigger is going to break, it has the potential to be more accurate and faster, but it also makes it easier to accidentally or negligently discharge if taking proper precautions.