Hmm... i suddenly have this urge to try using Aeris in the Battle Arena... Great Gospel should be worth a few battles to see there at least.. this plan seems to work well in my mind..

In Disc 1, spells like Trine and Beta would be doing tonnes of dmg to a chunk of enemies.. but usually my characters wouldn't be able to spare the Mp to keep spamming them continuously, while keeping defensive magics up...

however... Aeris seems to have the perfect cure for that.. if she takes too much damage, a Great Gospel not only buys time to recast protective magics.. It restores Hp and Mp of Aeris back to full..

This would certainly be an advantage over my Cloud, who seems to have troubles juggling dishing out damage, and keeping alive..

of course this is only in theory, and i have yet to test it out first-hand.. But i foresee the only potential problems would be the typical Petrify/stop problems (Which can be countered with a Jem ring) or All-Materia Break (which would really depend on what we're facing.. although the lost of the Hp-plus materias on her could be quite devastating)