All of our invoices and reports are built for the web and then converted on the fly to pdfs and emailed out to clients who prefer them that way. You lose the interactivity, which is a shame for some d3 reports, and you have to be a little careful (design for page breaks, test it as if it's a slightly fickle browser that you have to support, ensure that everything is visible without requiring interaction) but it keeps all of your development within the same tool stack and gives you web versions of them all for free.
Oh, I looked into it, but if you compare with LaTeX, its pretty simple, but we need references, and footnoes, and complex tables, so we would need an extended version, and preprocess it, and.. might as well use LaTeX.
But the need to produce good PDFs killed the idea.