I really like the "manual of arms" for the PPK. I think it is the best M of A for CCW (despite the fact that I don't generally carry one).
Here's why.
You can apply the safety on an empty pistol. Insert loaded mag, rack the slide (pointing in a safe direction). The hammer flollows the slide down. Top off mag as needed. You now have safety on, hammer down but blocked from firing pin, and a loaded chamber and mag. A very safe condition.
To put the pistol in operation, you draw, flick off the safety as you draw, and make the first shot DA.
The advantage over DAO: you have a safety on. If the trigger accidentally snags or gets operated, the safety will (should) protect from discharge. In a DAO, if the trigger is moved, the gun will fire. That's the one concern I have over Glocks.
The advantage over SA: if the safety is acidentally swiped off, you have a hard DA trigger pull to overcome before an ND. In a SA pistol, if the safety is acidentally removed, little pressure on the trigger will cause a discharge.
Safer on both counts.
The disadvantage over DAO: you have to remove the safety before firing. Training.
The disadvantage over SA: the hard DA first shot. In a defensive situation, the difference between DA and SA shouldn't affect your POA that much. If the first shot is at 25 yards, then thumb cock.
So why don't I carry my PPK (clone)? Because my P-11 carries 3 more rounds of a bigger caliber in a shorter, lighter package. But I wish the P-11 had a safety and a M of A like the PPK.