The BB doesn't truly shine till you visit Bahamut. I've killed Chaos in 3 hits with a Master, level 30ish (if I remember correctly, it has been a while). By that time, he is usually doing 700 damage per turn.
I have to say that if you're playing a game of practicality and ease, Red Mages are superior, as they make outstanding fighters and can cast the important spells. Sure, they can't use Nuke, but honestly, no use really makes good use of Nuke because you only have 2 or 3 casts for it and you certainly aren't using them on anyone before Chaos. So if you use a Black Mage, and his turn comes up and you're not fighting a boss, you pretty much have to waste his turn, one way or another. You just use a Heal Staff and restore 19 hp to everyone, or have him attack and do 5 damage, if he hits at all. Black Mages do make short work of bosses, though. I mean, it doesn't take a lot of Lit 3 to take down Krakken. Plus, "Fast" is a black magic spell, and that is the source of my Master's powers. But I think that Red Mages/Wizards can use Fast. I know they can't use any of the Harm Spells, and they have gotten me out of many a geist-filled jam. What decent spells can the Red Mage not use? I don't think he can use EXIT, and that's an important one considering that the Temple of Fiends Revisted has no physical exit. If you wanna leave and show the masamune off to all your friends, you'll need a White Wizard, because I'm pretty sure that not even the White Mage can use it.
When you guys refer to the Thief's "running skills", are you saying that the Thief has a better chance of getting a "Close Call..." than a BB or other class?