Test: GPT-6 Sol is cheaper and faster, but Opus 5.5 is more consistent

OpenAI launched GPT-6 Sol on September 22 at $2/$10 per million tokens versus $4/$20 for Anthropic's Claude Opus 5.5. Across three tests Opus 5.5 passed all 15 runs perfectly while Sol passed 12 of 15, yet Sol's runs cost $2.68 against Opus 5.5's $16.72.

• Sol costs $2 per million input and $10 per million output tokens, half of GPT-5.6 Sol
• Opus 5.5 passed 15 of 15 runs; Sol passed 12 of 15, failing two harder tests
• Sol's 15 runs cost $2.68, about 16% of Opus 5.5's $16.72
• On CI triage Sol was 8% of Opus 5.5's cost and nearly 5x faster