“The Player's Companion extends the core rules by adding a series of new classes, the dwarven machinist and spelunker, the elven ranger, and some human classes - mystic (monk), shaman (druid), and priestess. I'll come out and say it though, the thing that got me fired up with the book-love was the extensive list of templates. (I think they claim there are 144 of them). An ACKS template is basically some pre-selected options that speeds up character generation and gives the character a bit of early flavor. ACKS supports the old school roll-and-go - it's got basic 3d6 in order for abilities and simple classes, like classic D&D. The templates take it the rest of the way, by adding a preconfigured set of starting equipment, starting money, and suggested proficiency selections.”
I don't see why not. It's probably worth a roll on the Henchman Loyalty table because of the changing circumstances, though.
Within the context of the game world, the characters would each have to release the henchman from their service and then allow the other player to roll to recruit the new henchman.
From the meta-game point of view, you could simply allow the players (as compared to the player's characters) to swap control of the henchmen, leaving the in-game relationship intact.
The first option is what we ended up doing: it's risky to release and then try to hire again, but both players had the charisma and decided to go for it.
The henches ended up getting slight raises, though :-).
We've actually had this come up once...a Lawful retainer leaving the employ of what increasingly became obvious as a Chaotic Dwarf. I let her move over to serving the nice Lawful Cleric have her...but in part because he'd had no luck with retainers. When she levels she might leave the group entirely, we'll see how the Cleric treats her.