I love that idea. It:
1. effectively increases your healing spells. (the devotion 20/40/60/80 went away in the enhancement pass and bards have been lacking ever since)
2. fits bards much more thematically, amp feels more bardlike than something devout
3. Instead of buffing your own devotion, it's worded like a group buff. Even though a buff to your devotion would be beneficial to party members as well when you heal them, perception doesn't work that way, this is much better!
4. is also effectively a buff to other healers in the party. Alongside arcane might and inspire courage, a song that boosts healing makes healers welcome you as well.
It's genious!