So my primary class is ARC and I have been fighting Ifrit with it exclusively. I may not do as much damage as say a LNC but I definitely keep up. I don't understand why everyone feels that they have to change classes to something else to be "successful" in these fights. Yes they dropped the dps on ARC but it is no way useless. Being able to not get hit, drop a pretty decent DoT, and assist cure/raise when needed makes it a pretty good support package for the Ifrit fight.