You have to consider the reason for the development of the S&W DAO guns.
In my first armorer class, back in the 90's, when it came to the DAO part of the class we were told that the company had originally designed the guns for LE. That was back in the days when many LE agencies were still transitioning from DA revolvers to pistols, and there was a demand for revolver-like triggers on semiauto duty pistols.
While the traditional double action (TDA) pistols were DA for the initial shot, and SA for the subsequent shots (unless they were decocked back into DA), the DAO guns were designed to have a full DA trigger stroke for each and every trigger press. They were revolver-like for each trigger press.
You don't "partially" release a DA
revolver trigger, you fully release it so the trigger fully
recovers and the pistol is mechanically ready for another DA stroke. In other words, you let the DA trigger fully
recover for each and every DA shot.
In the TDA guns, after the initial DA trigger press the hammer remains cocked, which means there's a shorter SA trigger press next up for the subsequent shot. The design allows for a very short trigger/sear mechanical "reset" for the subsequent SA trigger mode (until the gun is decocked, and then you're back to the longer and heavier initial DA trigger mode).
Now, the DA trigger of the original DAO guns were pretty amazing for what they were, meaning DA only. Lighter, smoother and shorter than a S&W revolver DA trigger. Nice.
The newer DAO design (made for the TSW series), was made to be used with the standard shorter TDA slide, which couldn't cover the new style DAO hammer as much as the older DAO slide did, so it resulted in the DAO hammer not being "staged" ("located" is the S&W term) as far to the rear when the slide had been cycled. This meant a longer DA trigger pull to retract and release the DAO hammer.
The people who were interested in the DAO guns often preferred the shorter DAO triggers of the older guns ... but the newer DAO design allowed an agency to transition from TDA to DAO, if that's what they wanted, without having to buy new complete pistols. Their armorers could change out the TDA parts to the new style DAO parts and then have DAO guns ... or vice-versa, if they changed their minds.
Typically, shooters who were interested in DAO guns understood what they were getting, meaning DAO and no SA trigger mode, and the private owners who wanted DA/SA capable guns could still buy the TDA models, and get that typical short & fast SA trigger "reset".
S&W pistol enthusiasts didn't buy the DAO guns for SA trigger "short trigger reset", but for the DAO trigger operation. If they wanted a pistol with a SA trigger mode, with it's short & fast "reset", they bought the TDA guns.
It's kind of like someone buying a 1911 and then complaining it doesn't have a DA trigger (unless you bought one of the seldom seen Colt Double Eagles
).
It pays to understand how the different models are designed to operate, and then buying the design that interests you.
Know what you want, and then buy a gun designed and built that way.
Now, in the SIG model line over the years you could get a DAO (built for LE sales); a TDA model (DA/SA), which also has the newer SRT (Short Reset Trigger for SA mode) option available; or the Enhanced Double Action (also called the DAK), which has 2 different DAO trigger "resets", meaning 2 different lengths of trigger pull (after the initial full length trigger pull to fire the gun). In these days with the variety of newer DAO/DAO-like pistols being designed and produced, it can become rather confusing, granted.
