I've seen a lot of talk about controlability for follow up shots here. I think we need to remember that controlability is relative. Yes, a .45 ACP is more controlable than a .44 Magnum, but a 9mm is more controlable than a .45 and a .22 Long Rifle is more controlalbe still. Controlability, like power, eventually reaches a point of diminishing return. Eventually, you get to the point that you're trading a slight gain in controlability for a huge loss in power.
Another thing that must be remembered is that a difference in platform can make as much of a difference in speed of follow-up shots as the cartridge can. Very few people can accurately fire a revolver (the most common platform for a .44 Magnum) as fast as they can a semi-automatic. Likewise, many people can't handle a large-frame revolver like a S&W N-Frame or Ruger Redhawk as well as a medium or small-frame gun like a S&W L, K, or J Frame or a Ruger GP100, Security Six, or SP101.
Slamfire's example of the Super Blackhawk at the ISPC course speaks more to me about the platform than the caliber. Not only was he using a .44 Magnum for a game in which speed and accuracy are of much higher importance than power (so long as the power factor is met, power doesn't make much difference) but he was also using a single-action revolver which is certainly not the best platform for shooting at speed. Besides the obvious disadvantage of having to manually cock the hammer for each shot, the single actions grip is shaped in such a way that it causes the revolver to roll up in the shooter's hand and must be repositioned for each shot.
I'm not trying to say that a .44 Magnum is the best HD gun for everyone because it certainly isn't. However, I take exception to the notion that it's not the HD gun for anyone at all.