DeepSeek V4.1 Flash hands-on tests and comparisons

Under TP4 ring, 256K input and thinking on, the knapcio SGLang recipe matched MiaAI's SGLang decode and was about 23% faster in prefill, while the TensorFold build lagged.

The author ranks recent open-weight Flash models by hands-on experience, placing DeepSeek V4.1 Flash 1017 first ahead of Ling-3.1-Flash and MiniMax-M3.1-Flash.

Hands-on: Opus 5.5 orchestrates while deepseek-v4.1-flash-1017 runs sub-agents in Claude Code; 24 parallel sub-agents cost roughly $9 on DeepSeek, which did 99% of the work.

After 100+ hours digging through eval tasks and running closed-source tasks across frontier models, the author finds V4.1 Flash often on par with frontier models and 13–20x cheaper even when 5–8% behind; on Cursor bench it is 13x cheaper with fully open weights down to the inference stack.

The author says DeepSeek V4.1 Flash shows the third-largest drop from deepswe to frontiercode 2.0, behind Muse Wonder 1.0 and Gemini 4 Argon.

The author is cancelling GPT Pro over OpenAI halving limits on October 30, moving to Claude Max with Opus 5.5 as orchestrator and DeepSeek V4.1 Flash 1017 via Baseten at ~599 TPS for subagent work.

V4.1 Flash has led OpenRouter since Oct 25 at roughly 30% of token traffic, yet one GB300 rack could serve a day of its traffic; API is $0.15/$0.60 per 1M tokens off-peak.

OpenCode launches 2.0 and announces Operation Cheepseek phase 3, giving $80 of DeepSeek V4.1 Flash usage on a $10 monthly subscription, billed as the cheapest access anywhere.

On 14 complex php2shell vulnerability-finding tasks, Myhos 5.1 and GPT-5.6-sol got all 14, GLM-5.3 got 9, while Kimi K3.1 and DeepSeek V4.1 Flash each got 5.

A discussion thread concludes Chinese open models struggle with long-context needle-in-haystack and agent tool-call stability, though DeepSeek V4.1 holds up on single-file algorithms, regex and SQL.

A short usage note says pairing Opus 5.5 as planner/orchestrator with DeepSeek V4.1 Flash as the executor is the author's current go-to setup.

The author tries a DeepSeek V4.1 Flash 1017 IQ2_XXS-Uncensored quant on Strata, swapping the SSD-resident Engram part from 4-bit to original MXFP8 weights using only the weights already on hand.