I nuke pretty often even while main healing on WHM (and more should, as long as the fight is going well and the party is perfectly fine), so I'm not too keen on Tempest. It also doesn't help that Magic Accuracy is the only thing that determines whether Repose lands or not, but that being an issue really depends on your group makeup. If you can manage to get a Wand of X with 2x Healer's Hand III or IV materia I'd use that over the Tempest.