What the gnome said, usually you will just have DPS warriors taking it.
We had our prot warrior spec 5/5 Demo once when we had 0 dps warriors, and locks couldn't afford putting up CoW due to strict DPS requirements of sunwell.
Considering the amount of classes that can apply the AP reduction now (and yes, screech doesn't stack anymore) i don't really see the need for a prot war to grab imp demo shout, unless they put another Brutallus somewhere and your locks cannot afford using CoW, and you got no DPS warriors nor bears.
Worlde - Prot Paladin
Darkworldie - Tank DW Frost DK
Uord - Prot Warrior
Huordie - Feral / Resto Druid