That's the first thing I've ever read about Sig's accuracy. Guess I just got lucky with all 7 of mine - they're all more accurate than most of the other guns anywhere near the price (and I'm a CZ fan - I've owned 3 of them and still have a P-01).
I have come to the conclusion that my problem with Sig and accuracy is probably me. I've come to absolutely despise DA/SA triggers. The grip is a bit fat for my liking and I just never have been able to shoot the P220 well.
My CZ's on the other hand are a piece of cake. Feel great in the hand and the weight tames the snappy recoil of the .40 (which has an SA trigger). I shoot both well and can maintain 2.5 to 3 inch groups at 25 yards with either. I can only dream of shooting my P220 that well.
But I'll never get rid of my current P220 - sentimental value it has. Had it a long time, one of the 1st pistols I bought and like I said it has gone BANG! every time I've pulled the trigger (when it was loaded that is).