tl;dr: Benchmarking Kimi K3 (open) against Fable 5 (closed) across ~1,030 agentic tasks shows the two models perform comparably overall but specialize in different domains—K3 wins on terminal/security/crypto work, Fable on multi-language coding and data viz. Oracle routing between them achieves 93% accuracy while sending 72-96% of traffic to the cheaper K3, yielding up to 50x cost savings versus Fable alone. The takeaway: use a cost-optimized open model as default and route to premium models only for the long tail.