I own a P220SAO and it is a great handgun. I initially bought this as a .22LR handgun and bought the .45ACP conversion slide and mags. I also changed out the grips to Hogue Xtreme G10 grips. They are slightly slimmer and feel great!
If you have illusions that this pistol will perform like a 1911, you will be disappointed. The P220SAO is thicker and the trigger pivots, so it feels much different from a 1911 trigger. There is some very light slack to take up on the initial trigger pull, and there is a slight take up of slack on subsequent trigger presses. The trigger breaks crisply... no mush. The trigger reset is longer than a 1911 and probably about as long (in distance, not feel) as a Glock trigger. Trigger press is closer to 5lbs. It would be nice if SIG offered this pistol with a thinner trigger...
The really nice function of the thumb safety is that it can placed on with the hammer down or cocked. If the hammer is down with the safety on, you can #### the hammer with the safety still on. You can also manipulate the slide with the safety on, a great feature.
Mine is very accurate and is a pleasure to shoot. Bought it from Questar.
Got luck and was able to buy a Milt Sparks Versa Max 2 holster.

Fits both P220 DA/SA and SAO with or without rails.