I'll mirror some other anecdata here: Not finding Fable to be amazingly godlike at actual coding, but it does seem better at planning, architectural thinking, and reviewing code. Used it to think through some longer form refactors that involve some product decisions and changes, and found it to provide more thoughtful feedback. However that's just my subjective experience, and I don't think it's provably that much better to make me want to go pay for API pricing when the free trial is over.

My plan is to make hay while the sun shines: get some planning in over the next week or so, and just let Opus take care of it when I get to actual implementation.