Error rate over time increases dramatically.
Generally i trust it to do a good job unsupervised if given a very small problem. So lots of small problems and i think it could do okay. However i'm writing software from the ground up and it makes a lot of short term decisions that further confuse it down the road. I don't trust its thinking at all in greenfield.
I'm about a month into the $100 5x plan and i want to pay for the $200 plan, but Opus usage is so limited that going from 5x to 20x (4x increase) feels like it's not going to do much for me. So i sit on the $100 plan with a lot of Sonnet usage.
There's also a $100 version that's indeed the same as the $200 one but with less usage.
It does.
I think it may be that $20/month gets you access to Opus 4 via https://claude.ai but not in Claude Code.