Wanna know the only bit of content that Warriors aren't viable? (and by that I mean VIABLE not "Optimal choice")
Turn 5 of the Binding Coils of Bahamut. The one piece of content that nobody, NOBODY has cleared up to now.

So yeah, WAR is viable. How willing are you to put up with bullshit others are going to sling at you and how much work are you willing to put in this game? That'll decide wether you roll WAR or not.

(not to say WAR couldn't use some fine-tuning still, but yeah)