I'm not a sophisticated LLM user, but nor do I have tricky usecases.

Opus 4.5 with a plan mode is enough for me: it asks clarifying questions to map out the design space, it covers fiddly parts, it generates good unit/integration tests.

I have seen it cheat by deleting existing tests, since it's single-mindedly focused on the problem I give it. I've not used an LLM-to-review-an-LLM, but when I've used an LLM to review my own work, it notices when there are unrelated changes in my commit/working copy.

Besides, all of your critique is how I've heard product managers speak of human developers! And a tool needn't be perfect for it to be useful.