While this is interesting and could be nice I was thinking a bit differently for new songs:

AOE party regen song
AOE party haste song
Physical debuff song

With a toggleable skill/stance that basically changes existing songs effects. So that would be 1 skill for 4.0 now. Named maybe the Keeper's hymn. Mage's ballad would become the regen, Army's would become the haste and foe the physical debuff, with the warden's paean becomeing maybe a damage up debuff on the mob or maybe a goad or something like a high potency heal.