Don't know enough about the Sig or S&W, but my brother and sister-in-law asked me my opinion about a compact carry gun and I gave it to them. They ignored my recommendations and went with the Taurus 709 with the "adjustable" sights. My SiL then did the responsible thing and went to a NRA instructor to get training and practice but couldn't get a decent group to save her life. The NRA instructor couldn't figure it out either.
Finally, they were able to visit with me and I took her to the range to try to figure out the problem. After letting her shoot it some, I asked if I could try it. I shot to a strange point of impact also and finally looked at the sights. The sights were adjusted terribly, so it was shooting waaaay off from point of aim. The screw head was so small, I didn't have the correct size screwdriver with me, so we called it a day after finally diagnosing the problem.
Fast forward to a year or so later and my brother brings the pistol to get adjusted. We work on adjusting the sights and can't get it to group worth a flip. After messing with it for a while, we finally realize the sights aren't really adjustable because it doesn't stay in place. I (guiltily) felt vindicated because I had advised them against the Taurus. Don't know if the model you showed your friend had the adjustable sights, but if so, glad he didn't pick the Taurus. My experience proves to me it's junk. The sights were completely cheaply made and untrustworthy.