Some raw numbers to begin: at level 9 you are going to buff your pals for +9 to attack (+4 inspire courage, +2 master performer and greater, +2 flagbearer and banner, +1 haste), +8 damage (+4 inspire courage, +2 master performer and greater, +2 flagbearer and banner), +30 ft movement speed, +1 attack at their max base attack bonus; this is only the BASIC buffs that came from banner, inspire courage and haste.
At level 9, you have
Inspire Courage (Su): [...] An affected ally receives a [...] +1 competence bonus on attack and weapon damage rolls. At 5th level, and every six bard levels thereafter, this bonus increases by +1, to a maximum of +4 at 17th level. [...]
How the +2 inspire courage became a +4 inspire courage?