I have used Fable to the full extend of the 20x subscription's weekly limit, for all development tasks on my iOS project.

It was working better than Opus for me. It more often implemented features well on the first try, where Opus needs a few rounds of improvements to reach a passable result.

I am not sure why it would be a waste of money "for most coding tasks", and how you could conclude so with any confidence when you did not even really use it aside from final review passes.