Tony,
I thought the whole discussion involved exposure -- or rather, proper exposure. I shoot black dogs and white dogs. I can't afford to blow out highlights or lose detail in the blacks. So, proper exposure -- regardless of ISO -- is essential. As you point out, the higher the ISO, the less exposure latitude you have to play with. And the more difficult it is to pull detail out of the shadows, for example, without a lot of stuff you'll have to fix in PP.

Oh, and Preston, I only shoot RAW and you cannot recover totally blown-out highlights regardless of what you do. You can darken them but there is no data there. As Jim points out, just because the histogram is blinking, doesn't mean they are totally blown but I also shoot weddings and when you have white gowns and black tuxes, you have to be very careful about not letting the gown blow out.

Tony, doesn't high-ISO remind you of shooting Kodachrome vs Kodacolor in film days? You'd have lots more latitude with negative film than with slide film in general and Kodachrome was very exposure sensitive.

Jim