Those "price per task" benchmarks seem to pre-suppose the existence well-defined requirements and acceptance criteria.
When that isn't available, and the task involves "understanding the problem", "deciding what I'm actually after" etc. iterations, I find price-per-token to still be a better predictor of cost.
When that isn't available, and the task involves "understanding the problem", "deciding what I'm actually after" etc. iterations, I find price-per-token to still be a better predictor of cost.