Most opinions I have seen of the Sigma are less than stellar. If you want a great gun go with the SD and if you want a fantastic one, get the M&P. There is a reason that the Sigma is $350 and the others are more. You get what you pay for.

I don't have any experience with the Sigma other than my Brother in law has one, and he has not had any problems with it that I know of, but most people hate the triggers. It may be a reliable gun though, anyone else want to chime in here?