I started out IPSC in 1995 with a 220 and learned fairly quickly that I was hamstrung by the 7 round mag capacity (definitley not a concern if you are going to shoot PPC or IDPA, and now it is easier to get 8 rounders). I kept my 220 and bought a Para in .45 which I later switched over to .40 then I bought an STI in .40 (both 1911-type platforms).
I must admit that I really like the feel of both the Sig and 1911. I don't prefer one over the other though.
As Hungry mentions above, single action only is a little nicer for accuracy when trigger press is an issue but this can be over come with lots of dry fire, a spring swap and verifying dry fire practise with live fire. You can't go wrong in IDPA with a 220 (or any Sig for that matter... or Glock or Beretta).
My 220 has a horrendous DA trigger pull but the SA is very nice. I also own a 226 that has a very nice trigger pull and I have carried both the 229 and 226 for LE/SWAT work. I have managed to actually wear out a 229... 90 000 rounds of factory through it. It was still ticking but the dept. armourer was worried about the trigger spring locator hole becoming more oblong than round
From having shot, trained and carried Sig's I have learned that they break in very nicely with use and become more slick (even trigger pull seems to lighten up... probably just smooths out).
My opinion.... Sig's are awesome and need no work maybe other than springs(mainspring only) right out of the box. Very accurate pistols, awesome ergonomics, never finicky (except with 185's as mentioned above). With 230 FMJ or 200 Semi wad it always goes bang!
Oh, I was an adjunct instructor for the Sigarm's Academy and I'm a Sig armourer (for what that's worth)... if you need some help, feel free to PM me.
Just my 2/100th's of a dollar!