I have one. It's my favorite pistol I own.

Don't know about ALL of the parts, the only thing I know is "not standard" is the slide. The slide comes a little higher than most 1911s before following the curve of the barrel around, thus presenting a slightly more "squared" profile.I too have a question about Sig 1911's. I was told (maybe incorrectly) that they are not standard in their parts. In other words you cannot purchase Wilson combat or some other parts to "trick" them out. Is that true or not? I ask because I really do like what I see in the Sig 1911's.
You no longer have it? Why?I had a RCS several years ago. It functioned perfectly for me.
I can definitively tell you is that the extractor is very different from "standard" 1911's. The sig has an external extractor. Other than that, not sure about other parts dropping in or not. I'd check in over at 1911forum.com and roll through the Sig pageI too have a question about Sig 1911's. I was told (maybe incorrectly) that they are not standard in their parts. In other words you cannot purchase Wilson combat or some other parts to "trick" them out. Is that true or not? I ask because I really do like what I see in the Sig 1911's.