Verdict
Built from the measurements below
- Accuracy is too close to call: Gemini 3.8 Flash scored 82.5% and Muse Spark Open 77.5% on the same 80 questions, a gap within what chance alone could produce.
- Gemini 3.8 Flash is 1.2× cheaper per question as billed ($0.0037 vs $0.0045), reasoning tokens included.
- Muse Spark Open generates text 1.5× faster: 220 tokens per second against 142.
- Muse Spark Open starts answering sooner: 0.5 s to the first token, against 3.2 s for Gemini 3.8 Flash.
Which should you choose?
Choose Gemini 3.8 Flash for the lower cost per correct answer ($0.0045 against $0.0058). Choose Muse Spark Open for faster streaming, a quicker first token, open weights you can run yourself and more hosts to choose from on OpenRouter (6 against 2). The widest subject gap is in law: Gemini 3.8 Flash answered 6 of 6 correctly, Muse Spark Open 4 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap +5.0 points (z = 0.79). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.