Would it be unbalancing to allow an alchemist archetype that used Charisma instead of intelligence for bombs and extracts? What about just for extracts? The fluff is that the alchemist compels or uses magic spirits to power their abilities rather than pseudo-scientific stuff, but the action economy would be mechanically identical.
I raise the extract alone issue because the player wants to play a rogue-replacing beast-morph vivisectionist but wants to re-flavor it so that the beast shape stuff is about using animal spirits and stuff.
Thoughts?
What would replace what? Archetypes always give a specific exchange.
For a single classed character it would be a slight downgrade to go to all cha instead of all int for class features, as int is a more generally useful stat. If some features will use cha, and some int, that is a certain downgrade, as now you are needing two stats to boost your stuff.
When you conisder multiclassing and oddball race adjustments, the relative utility of various stat modifier mixes gets harder to gauge, but it certainly opens up combos that would not have been feasible otherwise.
Overall I would think it is fine, but take a gander at the whole picture.