These are also just what SAAMI states. If you look at what competitive IPSC shooters are doing for Major power factor in Open pistols, they're pushing 9x19mm pressure to very high levels but they're also using specialized pistols that can take the pressure, probably something your run-of-the-mill plastic framed 9x19mm pistol wont do well (they do it because the brass is cheap and many people just throw it away).
I don't/won't ever load .357 Sig and won't own either a .40 S&W or .357 Sig handgun. However, the above quote is fraught with fallacious information.
The frame of a pistol has nothing to do with that pistol's ability to "handle pressure." A Glock 9mm is designed to shoot +p 9mm forever, with no pressure-related failures. I currently have my daily carry G26 loaded with +p+ Ranger Talon 127gr ammo. I have no fear that my G26 will turn into a grenade when fired.
I wouldn't put a lot of stock in kinetic energy @ the muzzle figures, as those figures are largely irrelevant for s.d. purposes...well, that is, except you to get to enjoy more recoil, muzzle flip and muzzle blast.