Single click on your pally takes care of pretty much any damage shield on a mob. I'd not waste a bard song slot on it. About the only time I'd consider using a 2nd bard is to have one for a pure caster group to pump spell damage and click 3.0 for increased DPS, and maybe alternate casting 4.0 + for mana, if you need it. Most dont after the caster necks and class-centric mana recovery abilities.
tempest blade is much more effective in a group of pet classes because pets weren't effected by the attack delay so you will get more DPS return from TB in a group of pet classes since they are hitting more often.
Only downside to this is having to play a pet class
Maybe its because I am only as far as T5 atm, but right now, for me, pet classes are a waste of space.
All in all I see diminishing returns on a boxed team any larger than 6 to 8 characters anyway. Any larger and its just too big a hassle to manage (in T5 at any rate). I kill almost as fast with 1 solid group of 6 in T3/4 and T5 as I do with boxing 12. Adding another group to a T5 run cuts my clear time by less than 10 minutes. Not worth it unless I want to give a group kill credit....and I think you can still do that just parking them at zone in.
