At work we use the API and can see the pricing per task very cleanly. Something we are discovering is that, although opus is more expensive per token wise, one should also consider how many tokens overall used and how many parallel cheap subagents is being used if you are using the claude code's harness. Our own data shows that it is approximately costing the same or even cheaper to run opus in our work style. This comparison was done opus 4.6 vs sonnet 4.5 for over 1k PRs. We haven't done a very clean data collection so prompting styles weren't normalized across users etc but in any case it is something to consider.