I hate plastic guns, but of what you described the Springfield XDS and Glock 30 would probably fit best. Consider the Glock 36, too.
The XDS and 36 are single stack and hold 5+1 and 6+1 respectively over the Glock 30's 10--but you can get magazine extensions for both and the Springfield's is molded to resemble the grip.
When it comes to CCW, double stack 45s are chubby and that may affect your ability to grip it. All 3 have a trigger safety and the XDS has a grip safety (1911 heritage?). None have night sights for a 500-600 price point, but you can easily buy and install them for less than 75 bucks. All 3 shoot similarly, that is not terribly.
Back when my job required me to commute to some nasty places, I carried a Glock 30, I have traded it since for a Sig P226 (which has a proper hammer and DA/SA). I don't really think any of the plastic Sigs are worth carrying--I think the P250 is crap. I also had a USPc 45 in DA/SA, later converted to DAK, I also thought that gun was worthless.
If my life depended on a plastic sidearm I'd go with Glock, then Springfield, then Kahr. I've shot all four, and even a P250.
Opinions are like buttholes.
Last edited by thedudeabides; December 9, 2012 at 08:37 AM.