When you go do Ifrit's, I suggest you take more people than you really need, and don't bother trying to Sneak / Invisible your way though.
Every ZM5 alliance I've gone with tries to Sneak / Invisible their way through Ifrit's Cauldron. Bombs aggro to casting. Invariably, someone's Sneak / Invis wears off at a bad spot, someone forgets oils, someone casts too close to a bomb, the alliance is spread thin, people die, and it takes forever to get where you need to go.
Instead, make sure you take at least 3 DRKs or BLMs with you for Stun. Just cut a path of destruction through Ifrit's, killing everything in sight. This keeps the alliance together, and keeps everyone safe, plus it's a good chance for skill ups. The only thing you have to watch for is Self-Destruct, but BLMs or DRKs can easily handle that with Stun. (Other melee can too, with Stun WS's if they are paying attention).
It's slower if you stop to kill everything than if you just run through with Sneak, Invis, and no aggro, but that almost never happens, and by the time you take into account the time required to kill off links, raise the poor fool who aggroed, wait for them to recover, etc., it's just as fast, and a lot more fun, to just kill everything along the way.