My trick for using Opus is using it exclusively as a subagent managed by Fable.

"Use Opus subagents for this work where possible" is all it takes generally.

In my experience Astra/Sol are both quite good as workhorses, but not at Fable's level. I use them every day very successfully and I'm very picky.

Quite good as work horses? To me Luna is the work horse and Sol and Astra are prancing thoroughbreds. If I use Sol or Astra for anything other than curated reasoning and planning I will burn through my usage limits in an hour.

I used to do this but recently I switched to having Fable 5.1 spawn forks of itself rather than Opus subagents. Yes it's more expensive but you don't pay for reads that already happened pre-fork, and you end up doing less rework since Fable agents are just much smarter.