Well I Decided against the used Sig. Call me silly, but I just cant shake the bad vibe I get when thinking about relying a used gun as a duty gun. I like to break in my own guns and know exactly how they have been treated. There were a few other factors like not wanting to spend an extra hundred and fifty, plus my glock for a used gun, and 40 something ounces as opposed to 29 ounces for a gun that will be carried daily, and no warranty if your not the original owner.
As for an XD, I shot an XD .45 awhile back and hated it, I just couldnt shoot it very well. Ive also shot the ruger and loved it. I know there are a few police agencies that have issued these so I think a security guard will be just fine with one. And for the record I am open to a M&P, but I dont think that a manual safety is available in CA, and that was the one feature that I always missed with my glock.