I might be convinced, but I don't see it. IMHO, use of deadly force is not something that can be trained, even for LEO's. It's instinctual. If you truly believe your life is in danger and you have no exit and you are willing to take a human life, deadly force rules of engagement apply. Luckily, most jurisdictions still cast the law this way.
I believe a "Deadly Force" Forum will quickly move from appropriate uses to after action "legal survival" tactics. This can be summed up in one sentence: Speak to no one
but your attorney.
Like I said, I can be convinced otherwise. But I just don't see enough substance here to warrant a separate Forum. Mas Ayoob would, of course, disagree.