A comparison of Kimi K3 and GPT-5.6 Sol on the DeepSWE benchmark reveals that while GPT-5.6 Sol leads in single-shot quality (72.7% vs 68.5%), Kimi K3 achieves higher pass@k scores for k > 1 at a significantly lower cost.

  • Kimi K3 wins pass@2 (82.0% vs 81.0%) and pass@4 (89.4% vs 85.8%), reaching the best pass@4 of any flagship-tier configuration.
  • Kimi K3 costs $4.65 per rollout compared to GPT-5.6 Sol's $8.37, delivering 2.8x more solved tasks per dollar.
  • The models diverge significantly (0.46 correlation) and fail differently, allowing a Kimi-first cascade with escalation to Sol to cover 108 of 113 tasks.
  • GPT-5.6 Sol is more reliable, solving 61 tasks four-for-four versus Kimi K3's 45, but takes longer per rollout (17 minutes vs 66 minutes).

Routing between the two models provides a strong practical solution, with a Kimi-first cascade reaching about 85.6% accuracy while being cheaper than using GPT-5.6 Sol alone.