Ive just aquired the BARD job for Archer and i cant help think you'd be better off just staying as an Archer, the BARDS abilties really arnt that Vital to changing a battle for you or your party, and why you might think, "but at least your getting something extra" you've actually lost a lot more with the CROSS-CLASS abilities.
For instance, Ive also leveled the White Mage to Level 50, so with the Archer i was able to use RAISE, CURE, PROTECT and STONEWALL as a CROSS-CLASS abilities but since becoming a bard im no longer able to use these. I cant say how many times Cure and Protect have helped me out as a Archer class, and on one occasion in the boss fight in Haukke manor i was able to raise our conjurer which massively helped out. The abilities with bard just arnt that important and you have to stay close to the players for the effects to stay active.