No, I understand you loud & clear; I just disagree on the proposition that one must put *all* one's eggs in one basket, which is fundamentally what the Big Bear Magnum concept is fixated around. Not to mention how much more likely a given shooter with such a gun is to develop a terrible flinch during practice, or pull the gun off-target from a heavy DA revolver trigger. Certainly not insurmountable obstacles, but obstacles nonetheless.
You've also brought up 'spray and pray' for at least the second time, despite the fact that lighter-recoiling chamberings are far easier to shoot quickly as *aimed* fire. Not to mention the training/flinch aspects I already brought up. Lastly, if you only have a fraction of a second to line up a shot (which is the timeframe I assume we have to work with if there is truly only an opportunity for one discharge) a heavy steel N-frame S&W revolver is about the last weapon I'd want to have to rip up out of a holster in front of me & quickly align the sights --again, a lighter/handier weapon is faster in every way, therefore its effectiveness is positively augmented even if less powerful (whether that's ultimately enough to matter is another issue that needs a lot more real data on both sides of the argument to convince me either way).
So, to circle back around to the 'core' of my Devil's Advocacy, the notion that a shooter would be limited to the same "one shot" mentality offered by a big magnum revolver when considering hypotheticals, simply does not make sense. Which is why I submitted that there are very real advantages to having more 'chances' (follow up shots) even with a less powerful bullet,
but that far more important are the unavoidable disadvantages of speed & power for either type, that fundamentally make all handguns ill-suited to this type of task. Just use something with a stock, that's more powerful than a big magnum, as fast as an autoloader for followups, and easier to aim than either (as well as use for a club if need be)
TCB