Badass. Diaga is really good, I'd actually hone it to R3 (I have the orbs), but I want to save my Holy Orbs for Ruinga. I can -also- hone Quake to R4, but I also have plans for those Dark Orbs.
In other news, I just honed Waterja to R3. Suck it, Gandhi.
EDIT: In all fairness, White Magic is just about the most self-sufficient skillset in the entire game. Two very good status spells (Slowga and Silencega), niche ST buffs, utterly badass MT buffs, the obvious healing usefulness and even competent, cost-efficient offense (the two extra castings on the Dia line go a long way). The only thing they truly lack is MT offense, which many healers (like Vanille, Garnet, Yuna and shortly later Eiko - hell, even Aerith in the foreseeable future) cover with other skillsets. Don't fuck with the clerics.