Well, I have actually gotten my hands on two of these this week-a SA compact RO (although this one was a 9mm), and the Sig C3. The Springfield was at the LGS, and it felt pretty good handling wise, though I know the 45 would be ever so slightly different in size I suppose; and figured out that a coworker actually has the Sig C3, so I got to run 20 rounds thru it earlier. It shot great and smooth, and I can get my whole pinky on it with the smaller grips, but there sure aint any extra room...seemed nice and light to carry as well.
I carry a C3 daily, holster by Ryman holsters out of KS. I've really enjoyed the gun so far, only problem is the holster selection can be few. The slide profile on the Sig is a different shape than standard, so not all off-the-shelf holsters will fit correctly. As far as fit and finish go, I love the slide finish on the C3, shows no wear since I've carried, going on 8 months now. The fit is tight, but still very easy to disassemble off the shelf. You won't go wrong with one!
I use both a Dan Wesson ECO in .45 and a DW Guardian in 9mm. The Guardian is a little long but it shoots so nice and with the lightweight frame its like its barely there.