The theif being good at escaping from battles is a complete myth. Though I agree with Fi/x/Rm/Wm probably being the most solid basic setup.

I just played through with Fi/Bb/Rm/Wm and interestingly enough it turned out to be Fi/Rm/Wm/Bb. Yes, the White Mage has consistently better defense than a Black Belt through the entire game. All and all I would rate it good, but still worse than Fi/Fi/Rm/Wm.