Lot's a folk don't mind acquiring iron for the sake of it, but for me there's not enough gap between a Ruger 1911 and the Springfield Loaded/Sig. I'd have to move up to a TRP at least.
It should be pointed out that Sig offers a round top slide in their "Traditional" line of 1911's.
Kimber seems to have forever tainted the external extractor on a 1911. S&W and Sig versions work just fine on 1911's, as do externals on almost every other semi-auto offered.
