If Fable gets correct answer quicker, then you might pay less than doing back and forth with Opus, plus you lose more of your own time.

I see no reason for using less able models in my workflows. There is this saying, penny wise and pound foolish

same as it ever was. It seems your argument implies a belief that you should always use the best model. Others think that not all tasks require the absolute most powerful, expensive, model.

The CursorBench plot, for example, shows that fable does have slightly better performance, but Opus is pretty close, and is less expensive per task

fable on longer coding tasks with fable subagents will easily chew through hundreds of dollars in a single run.

less expensive per task might also mean less of your own time