Here's an example, the Beretta 92A1 is DA/SA. After the slide is racked the first shot is like 12 or so pounds of trigger force (don't quote me on that)...(assuming you dont cock the hammer back manually) after that first round, trigger pull is practically nothing! 4 pounds or so. It takes very little to pull that trigger. Personally i would never carry my 92 in SA. Too paranoid. But carrying the xd9 sc with one in the chamber, doesn't bother me a bit. Its got the back strap safety and the trigger safety. It could fall to the ground and I'd have enough confidence that she wouldn't go off.
All depends on the gun I suppose... Hope I could help!