357 sig is not for everyone. Plus the ammo isn't cheap. 9mm is plenty fine as a man stopper with the right ammo. 357 is just a hopped up 9mm after all. You can get +p+ ammo for 9mm that is very close to 357. I believe the key is to find what the shooter is competant with and likes to shoot often. Shot placement is key for stopping with a handgun anyways. We all know it isn't like in the movies!