Qwen3.8-Flash-Next runs close behind Claude Opus 5.5 in a six-way coding benchmark
A Reddit user (deepu105, r/LocalLLaMA) ran a controlled comparison on one real Rust feature from the LlamaStash roadmap, testing six model-harness-effort combinations twice for 12 pull requests; Flash-Next ran locally on a Strix Halo laptop (Flow Z13) via Halogen at roughly Q4 quantization, while Opus 5.5 ran through Claude Code. Claude Code with Opus 5.5 at xhigh effort scored 6.94 of 8 (87%) in 43.5 minutes at $17.78 of API cost, while Claude Code with Flash-Next at medium scored 5.5 of 8 (69%) in 45.3 minutes; the author reports Opus averaged 82% on code quality versus 68% for Claude Code + Flash-Next and 66% for Pi + Flash-Next, with the gap concentrated in edge cases, tests and documentation. All 12 runs finished and all 12 PRs passed the end-to-end test, and the author notes the models are not in the same league since Flash-Next ran quantized on a 70W-capped laptop.
Reposting again since original post got removed by Reddit for some reason (I have no idea why)
A few of you pointed out in my last post that comparing Flash-Next and Opus with different harnesses and effort levels wasn't fair. So here is a more controlled comparison.
Same task for every run: a real feature from the LlamaStash roadmap (save llama-server's KV cache before an unload and restore it when the model comes back). Six combinations, each run twice, so 12 PRs. Flash-Next ran locally on my Strix Halo laptop (Flow Z13) via Halogen (~Q4 quant). Opus 5.5, Flash-Next, and Kimi K3 scored every PR on seven review questions plus CI.
| Combination | Score (of 8) | Time | API cost | Tokens (in / cached / out) |
|---|---|---|---|---|
| Claude Code + Opus 5.5, xhigh | 6.94 (87%) | 43.5 min | $17.78 | 507k / 48.3M / 203k |
| Claude Code + Opus 5.5, medium | 6.25 (78%) | 23.4 min | $6.52 | 242k / 13.4M / 95k |
| Claude Code + Flash-Next, medium | 5.5 (69%) | 45.3 min | $0.32 | 445k / 13.5M / 82k |
| Pi + Flash-Next, xhigh | 5.44 (68%) | 63.8 min | $0.67 | 316k / 35.0M / 134k |
| Claude Code + Flash-Next, xhigh | 5.38 (67%) | 49.5 min | $0.39 | 269k / 18.9M / 99k |
| Pi + Flash-Next, medium | 5.06 (63%) | 48.1 min | $0.56 | 242k / 29.1M / 117k |
#Qwen3.8-Flash-Next#Claude Opus 5.5#Claude Code#Pi#Kimi K3#LlamaStash#QwenCloud#Halogen