In a discussion of Pro Difficulty unlockables... I felt an important tool (and hence a valuable unlockable) was "a non suspicious explosive" (in the thread I suggested a knapsack bomb).
Considering even the benign breaching charge causes alarms, The Big One can have potential value in Pro Difficulty as a "free" fire accident catalyst. It's certainly better than the most common method which is, you risk having to pull out a gun and shoot the puddle or the generators.
Is it remotely triggered? I think if it is... it would be golden (situational.. but golden).
Also.. speaking of the breaching charge.. can The Big One open doors? blow out windows? cause chandeliers to drop?