The minimax-m2.5 case is the one worth flagging hardest for anyone building a router across a model pool like this. A 200 that silently does nothing is worse than a 400 -- a 400 fails loud, a silent no-op just eats a budget you thought you'd capped. Feels like the only safe pattern for a heterogeneous pool is a canary: run one known reasoning-sensitive prompt per model/param combo at setup and check the measured token count actually moved, rather than trusting the response code to mean the parameter took.