I would be happy with a top5-enemy-healer-list in any BG really, be it WSG or AV. But seeing that some warriors does alot of healing, and some other classes too, check their dps vs healing, and if dps is higher, dont put them on the list. :) If this could be implemented to nameplates, so that whenever a unit with the same name as anything on the list is close, they would get a border around them, or a glow or even change color, that would be sweet :)
But I dont know it its a secure check. Would wow lua be able to color nameplates incombat from a static(read; pre-combat made) list?