Jim, Tony,
isn't it the same as saying that you expose for highlights knowing you can bring up the shadows in PP? When I shoot formals, that's pretty much what I do. White dogs get exposed so I can see the details in the fur knowing I can balance the darker parts of the image in PP. Black dogs get exposed so I don't blow out the details in people's faces but knowing if I've lighted them properly, there will still be plenty of detail in the dog.

I realize I don't shoot high ISO when I'm doing formals and at high ISO, you don't have the latitude of lots of stops of exposure but the concept is still the same. Which is the Velvia comparison: very little latitude in that film so exposure was always super-critical. But the issue ultimately is dynamic range and no film or digital camera sensor can capture every level of exposure from pure white to pure black. Something has to give and you, as the photographer, have to decide what it is: blown highlights or clogged up blacks. You simply can't get it all at any ISO.

Jim