I think that the .500 S&W was designed by a group of engineers that wanted to prove to the world that their johnsons are bigger than Dick Casull's. This is a classic case of penis envy manifesting itself in the form of firearms cartridge design.

IMO, the .500S&W is just another example of recent cartridges introduced as a solution to a problem that doesn't exist. There is NOTHING that the .500S&W can do that the .454Casull can't. The .454 will take down almost any game animal in the world (excepting maybe the largest dangerous African game). And the .454 Casull does it with a lot less recoil and provides non-masochistic shooters the option of shooting .45 Long Colt ammo when maximum performance isn't necessary or desired. The .500S&W is power for the sake of power; essentially "Magnumbitis" run amok.
If you desire such a pistol and truly are able to tame such a beast and shoot it well, then by all means go for it. I'll stick to a .454 Casull and I don't think that I'll ever feel undergunned.
Mike