I have very rarely seen THM use Resonance, even though it is 'their' ability.
However, I use Resonance ALL THE TIME as CNJ, especially on fights where it is really unwise for me to move at certain times, such as Ifrit and Moogle. Do I need to heal someone without moving into the danger zone of a potential plume, eruption, or dash? I'll just use Resonance and heal someone from the other side of the room. With Moogle, it's useful for when the group is fighting a mob with a bad AoE (Thief of Black Mage) and I'd rather not risk it by running too close when I have to heal the tank.
But, for THM? It doesn't have too many uses. I'd rework it to give it to CNJ, and give THM something else... although, I like all of my other abilities on CNJ, use them on a regular basis, and don't feel like giving them up...
