.357 Magnum is like 9mm, in that the three most common weights, 125 grain, 158 grain and 180 grain in .357 Magnum and in 9mm 115, 124 and 147 all preform about the same in the real world. There are many ballistic formulas and there is ballistic gelatin and shooting results, on animals and humans to back that up too.
Look at the 125 grain .357 Magnum versus the 115 grain 9mm. Like Dragline45 said, do you really think ten grains and two hundred fps create some sort of magic threshold of power?
No, there is nothing wrong with a .357 Magnum for defense, but a 9mm Parabellum loaded with eighteen premium hollow points can easily be argued to be of more combat utility than a revolver loaded with six-eight.
"No free man shall ever be debarred the use of arms."- Thomas Jefferson