I have tried the SAO.
I bought one thinking I would love it, and sold it right away. The thing is, I like 1911s, and cocked and locked is best for me, and Sig did that well with the P220 SAO, but the 1911 did it better.
The whole draw to Sigs, which I seem to have forgotten when I bought that one, was the double/single ability. No .45 does cocked and locked better than the 1911. The SAO is only available with a rail right now, and I really don't like those on my guns.