So if you're "seriously" trying to damage an HNM you'll have 2 bards (or a rotation) and a cor and not be fighting Odin. Gotcha.
For the record, a Sam with only 1 bard getting march+ballad+haste in a tank party already does far far more damage than any black mage can hope to do on Tiamat. I'm not going to debate that more buffs would make it that much better, but saying you'll always have 2 marches 2 minuets and chaos roll is a bit silly, in my personal opinion. Oh, and in the above situation on Tiamat, you're not "not trying to deal damage".
Also, where did you get 450 defense? Because according to Araelus(sp?), HNMs have far more than 450 defense.
http://img21.imageshack.us/img21/1075/defstuffcopy.png
It's okay though, we're used to your propaganda.