One of the posts that was lost in the recent server changeover included a suggestion that one should try shooting both the 9MM and the .357 SIG before deciding.
That's a good idea, but there is one important caveat: one should not make a judgement on the basis of range shooting. Rather, it is important to try both in high performance pistol shooting, using multiple targets and a timer. The important question is
how one does in terms of time required to get multiple shots on each of multiple targets.
One should not confuse noise, blast, flash, recoil, muzzle energy figures, and how water jugs react, with real effectiveness. It should be understood (1) that most modern service rounds are quite adequate and having more punch than you need will likely work against you; and (2) that with one or more rapidly attacking assailants, speed in making multiple hits is of paramount importance.
When one reads accounts of police officers hitting suspects five or six or even a dozen times before they go down, that's because some of those hits involve injuries to a wrist, ankle or calf, and because some involve multiple hits to the same lung, for example. Two things about that: (1) more energy usually won't help; and (2) it does not happen because police officers do not shoot as well at the range as others, it's because of the nature of a rapidly unfolding fight, which would affect any of us in a real world encounter.
Those who try a handgun at the range and conclude that, because they can hit targets with it, it is sufficiently "controllable", really need to try some timed rapid fire at multiple targets. People who are enamored with muzzle energy figures should consider the conclusions set forth in
this FBI report.
Some relevant excerpts:
Few, if any, shooting incidents will present ... an opportunity to take a careful, precisely aimed shot at the subject’s head. Rather, shootings are characterized by their sudden, unexpected occurrence; by rapid and unpredictable movement of both officer and adversary; by limited and partial target opportunities; by poor light and unforeseen obstacles; and by the life or death stress of sudden, close, personal violence.
Kinetic energy does not wound. Temporary cavity does not wound. The much discussed "shock" of bullet impact is a fable and "knock down" power is a myth. The critical element is penetration. The bullet must pass through the large, blood bearing organs and be of sufficient diameter to promote rapid bleeding. Penetration less than 12 inches is too little, and, in the words of two of the participants in the 1987 Wound Ballistics Workshop, "too little penetration will get you killed." Given desirable and reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound by increasing the size of hole made by the bullet. Any bullet which will not penetrate through vital organs from less than optimal angles is not acceptable. Of those that will penetrate, the edge is always with the bigger bullet.
Personally, I do not need to conduct such an evaluation for myself. The issues of the greater muzzle blast and penetration indicate against the .357 SIG for home defense, and my conclusion that the 9MM is adequate for personal defense makes my decision a simple one for concealed carry.