I rise from my grave...to ask y'all a question. I'm gonna be running this and I've been looking at the statblocks of the NPCs that made me pick this AP to be the AP I run to get my skills up to snuff. Unfortunately it seems the custom bug bit me yet again (I can't even run a simple monster without changing the feats on them.) So before I give into my urges I wanted to see if reclassing anyone would break the campaign. Anyone that gets a reclassing would still be true to the character's core, Sandru would still be a swordsman with a smile and doginess to spare, Shalelu would still be at home in the woods and skilled with a bow, etc.
Sandru: Actual Swashbuckler (though that's mechanically pretty lame), Standard Bearer Cavalier/Scaled Fist Sensei/Battle Herald (though the NPCs already have a source of Bardic Music unless you change that), Warlord (3PP).
Ameiko: Imperial bloodline Sorcerer (Don't let her reach level 16 if you do this. Otherwise she's just a Robe of Arcane Heritage away from immortality),
Koya: Easily the one the plot depends on having in-class the most. Her religion is important, and I think there's a few references to spells she can cast.
Shalelu: Nature focused bow user is largely locked into Ranger. Her one spell isn't important, so she could be a slayer.
My players bring an NPC of their choice with them on away missions, which has helped them feel connected to the NPCs.
In my game after Ameiko got the magic katana, she retrained to a Swashbuckler VMC Bard.
Sandru is a Rogue (Driver) archetype.
Koya is a Cleric/Witch aiming for Mystic Theurge (or was before she left the caravan to join Desna on some crazy extraplanar quest, which was mostly so the PCs would stop running to Mum for advice).
Shalelu is a Ranger/Fighter.