Hm. I like the concept. Biggest concern is that both the Exhaustion and Defeat mechanics look liable to cause a deathspiral - though I notice that Human Flaws might not be entirely disadvantageous, if they give you more leeway for Snapping productively.
I don't see any hard incentive for taking Organ flaws, and the soft incentive of 'descriptive leeway' only counts so far. I might consider allowing players to take a Perk when they take an Organ Flaw, as they mutate further from their initial purpose.
This mutation rate also strongly implies a short campaign; you'd accrue too many modifiers otherwise. Perhaps a stalling tactic where you use a Perk to cancel a Flaw would work, for longer stories?