....But isn't this like so much of this type of stuff..."some one, somewhere, said that you
need this or that" so "it" (in this case iso speed performance) , becomes absolutely, unequivocally necessary that we must have it.
The reality is more like some people, a minority, have a genuine need for this type of performance/capability from their camera whereas most will never use more than 800. Perhaps one day manufacturers will start producing cameras/sensors that will have a specific use eg) high iso noiseless performance....at a price. There may already be such products out there.
Unfortuneatley (or fortuneatley for some) the debate around these issues takes up a lot of energy and takes the focus away from what the mainstream performance capability is. Sells lots of magazines etc.
As always I think you just have to adhere to the age old principal of "buyer beware" and do your homework!
Cheers
Grant