I am making no attempt at attacking you. I am simply trying to impress my point that in a realistic scenario, one would hardly choose to shoot at ISO 3200 or 6400 at F9 when there is light available to shoot at ISO 400. Such is the case with what you offered. I simply do not feel that is representative of the question asked.
The orchestra pit example you've offered here is excellent and representative of the camera.
Your comment about ETTR is well taken, but is only possible when one has an abundance of light, or can sacrifice shutter speed or aperture (DOF) to get the shot.
The examples I spoke of are representative of what happens when you have a subject that you can get correct metering on, but the overall scene is quite dark or black. In my many years of photography, that has most certainly been the most common scenario where I have needed high ISO. A singer or performer on stage. A sports participant on a dark field, and existing light portrait under moonlight, etc.
I do apologize if it seemed as though I was attacking you personally. That was not my intent at all.