Outside of Abyssea, where Tanks don't have HP in the 4k range, Cure IV is okay. Inside of Abyssea, I might as well just come BLM to everything instead of RDM unless I'm soloing an NM (and an NM NIN/DNC can't take care of faster than RDM could, at that). Perhaps make a relatively easy-to-get Staff with:

Cure Potency +10%
Visitant Status: "Cure V"
85 RDM SCH

Or something like that. Though I'd rather have the spell natively.