Verdict
Built from the measurements below
- Accuracy is too close to call: GPT-6.1 Terra Pro scored 76.2% and GPT-6 Astra 76.2% on the same 80 questions, a gap within what chance alone could produce.
- GPT-6.1 Terra Pro is 2.7× cheaper per question as billed ($0.005 vs $0.013), reasoning tokens included.
- GPT-6 Astra starts answering sooner: 1.3 s to the first token, against 8.5 s for GPT-6.1 Terra Pro.
Which should you choose?
Choose GPT-6.1 Terra Pro for the lower cost per correct answer ($0.0065 against $0.017). Choose GPT-6 Astra for a quicker first token and shorter outputs (about 205 tokens per question against 453).
Accuracy gap +0.0 points (z = 0.00). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.