I am also very pleased with the Sig P938's I have shot. However a lot of people I know, do not like them. The pistol just doesn't fit well in their hand, or something. They claim it "wants to jump right out of their hands".
For myself, I have not had that issue with them. With cheap 115gr fmj range ammo, most have grouped around 3" at 5 yards. That opened up to 6-7" during rapid fire. In a carry pistol that size, is more than acceptable IMO.
One thing to watch out for, is the variety of trigger pull you might get. I haven't seen too extreme of a case myself, such as some guys reporting 12+lbs. However, I have picked up two different P938's side by side. One had a pull of somewhere around 5-6lbs (I don't keep my finger calibrated, sorry). The one next to it was probably closer to 9lbs.