Avoid the DAO, you don't want its trigger pull.  The gun doesn't require the heavy trigger pull to function, like all DAOs it is there for political reasons, so police officers can protect themselves from scumbag lawyers who will claim negligent discharges from the "hair trigger" of a single action.  The USG has a nice, sinlge-action type trigger pull that is a joy to shoot and promotes good accuracy.  After each shot the striker action resets itself, just as you said, like an internal hammer being cocked by the slide, so you get the light, crisp single action every shot instead of the heavy, long double action.  

Make sure you aren't confusing single and double action.  Think of an old S&W .357 magnum with a big hammer sticking out the back.  On the double action pull, pulling the trigger has to do two things, cock the hammer at first and then release the hammer once it has come back far enough.  A long, heavy trigger pull is necessary for double action since your finger is effectively fighting against the hammer's mainspring, which must be a strong enough spring to set off the gun's cartridge once the hammer falls.  On the single action pull, the hammer has already been cocked back (on an automatic this can be because the slide cocks it back automatically while traveling rearward after firing a cartridge), so you don't have to fight the mainspring at all and the length you have to pull the trigger is significantly reduced.  99% of shooters would rather actually shoot a single action trigger pull than a double action trigger pull.  99% of lawyers, police chiefs, and bean counters chew their nails over the idea of people carrying around guns that are cocked.  I'm in the 1% of lawyers who know what a 1911 is, but that's off topic.

Having shot both I must strongly say, you don't want the DAO.  Grab a USG model, there are several places that have them in stock.  The ones I have tried were at www.cmmginc.com, they currently have new in box USG's in stock for $900.

Roger that about the ammo.  New ammo came out in response to govt. pressure about the AP capabilities of the caliber, so FN played a couple of caliber games until the govt. pressure went away and the PS90 proceeded into existence.

These are the types:

SS190: Steel Penetrator, LEO only but not illegal to possess or shoot, just rare.  28 grain bullet at 2300 fps velocity.

SS192: Older type ammo which was put under attack by the Brady Campaign as being AP.  Discontinued.  Not illegal to possess or shoot, but getting rare.

SS196:  Newer type ammo which replaced the 28 grain bullet with a heavier 40 grain bullet loaded to a lower velocity, around 1600 fps.  Appeased the govt. until the AP controversy blew over.

SS197:  Newest ammo retaining the 40 grain VMAX bullet but loaded to 2,000 fps velocity.  This is real fast for a handgun considering the slightly increased bullet weight.

Supposedly, empirical testing by curious parties has shown the new SS197 ammo to zip right through commercially available body armor at CQB engagement ranges.  I haven't seen this for myself.  Shhhhh, don't tell Sarah Brady.

Fiocchi USA has begun production of the SS196 and SS197 ammo domestically, right here in the Ozarks near Springfield, Missouri.  This cuts down dramatically on the price of ammo since all previous ammo had to be imported from Belgium.  Trial runs have been done and commercial availibility should start soon, with pricing around the same as .40S&W.  The creation of the PS90 made this possible, Fiocchi probably wasn't sure of the demand for the caliber until they were certain people would be loading up 50 rounds of it at a time.  

For the Five-Seven, there are prototype 30-round magazines in existence right now, but commerical production of them is uncertain.

Quoted: Duke, From the research I have done & the questions I have asked, the folks selling the USG models on gunsamerica.com, well they all seem to say the the USG is the DAO model, including Impact Guns who I just got off the phone with. Are you sure the SAO models are available? If so, where can I find one.  Impact Guns went as far to say that the SAO model or the Tactical model as they have it listed, is not available to civillians due to a Gov't tax thing. And that they are for sale to Police Dept's Only. M4-CQBR

The one I played with at CMMG on Sunday was a USG model just like the one pictured above on their website.  It had a pretty nice single action trigger pull.  Not a 1911, but still pretty darn nice.  I think they had about 6 in stock NIB.