I've always played it as clerics deriving their power from faith in an ethos. In a traditional meddlesome gods set-up, the various ethea are set by divine command.
The only thing from D&D '24 I'm sure to adopt is the new conjure/summon spells. I'll look at other things and evaluate if they add any value, or if they might cause weird interactions.
Looks like they're using the herbalist kit as a catch-all for witch/animist/traditional medicine type things. Though, I don't see why you couldn't have Artisan Tools [Chandler] as well.