You can easily modify the Sigma's trigger pull to be much lighter. There are a couple of springs at the rear of the lever that's actuated by the trigger (can't recall the technical term right now). They consist of one spring inside another. S&W put them in there to deliberately make the pull heavier for "safety" reasons, or so I'm told. If you take one of them out it helps the pull immensely. Mine had a horrible trigger when I got it. It was like a formal dinner at the Adam's Family house - stiff and creepy. Now it's only mildly repulsive, still really long and gritty, but a lot lighter.
I don't think I'd try the lighter weight striker spring, because it really seems like it would reduce reliability. The only trouble I've had with mine is with Wolf ammo which apparently has hard primers. About 1 or 2 in 10 wouldn't fire.
Overall, though, it's a pretty good pistol for the price. Mine is reasonably accurate for a combat handgun, especially considering I don't really shoot pistols much. I can easily keep a full mag on a paper plate at 25 yards, which even though it won't win me any competitions is good enough to take down any goblins who break into my house.