Can you please provide a follow-up to this? How has the campaign been going? I ask because my party also is caster heavy.
Or, anyone else run this with a suboptimal lineup?
The first three volumes have gone superbly well, though the game is on a temporary hold due to real time conflicts right now.
I have to say, the last thing I would consider this party is 'sub-optimal'.
An Eidolon, a high strength Summoner with a long spear and multiple summoned creatures that can be tailored to foes you face make for great front line troops, especially when buffed by the Master Summoner (Haste) and the Arcane Duelist (Inspire Courage, Good Hope). At range the Wizard and the Archer Bard are plenty effective, as are flying summoned creatures. And then of course there's the Wizard's battlefield control.
The Bard has excellent social skills while the Wizard provides knowledge skills and the Master Summoner's eidolon has been built as a small, high stealth, high perception scout with flying. If anything, the party has proven to be a little too optimal.