Test: Claude Opus 5.5 offers no edge over Sonnet 5.5 for coding agents

A comparison of Claude Opus 5.5 and Sonnet 5.5 in Claude Code on six real coding tasks found both models passed every hidden test across all 24 runs. Opus ran 1.6x slower and cost about 2.5x more per task, $0.175 versus $0.069.

• Both models passed 100% of hidden tests, including 136 Mustache cases
• Average cost per task: $0.175 for Opus versus $0.069 for Sonnet
• Opus spent more time self-checking: 72 s versus 45 s on average
• QuickSilver Pro pricing: $1/$5 per million tokens for Opus and $0.5/$2.5 for Sonnet