I'm always worried about LLMs unintentionally affecting the actual content, so the extra effort of carefully reviewing the diff just isn't worth it. Markdown + PanDoc is more sensible to me if your document is simple enough.

I successfully converted a typst report to md/mdx last week using this technique. For complex layout primitives I just told the llm to write a comment with a warning todo of the missing part it wasn't able to convert

Well you can always diff the document. If it's not too large, then manually inspect it. If too long, then pipe the diff into the clipboard and send it to another LLM to summarise the changes.

The LLM are already good enough to not do that anymore. Worst case scenario, you get wrong formatting, but not wrong content.

Markdown + pandoc is not the same: you need already basic formatting. You have to think about the formatting. For example, math formulas and code are gnarly to type, so I have snippets for them to avoid getting out of the flow.

But LLM don't need that, you can just dump your thoughts, and they format it.