If one is going to write LaTeX code anyway, it seems easier and cleaner to use LaTeX all the way, move all the boilerplate along with the personal template to say, a file named preamble.tex, and \input{preamble.tex} in the documents.
However, there are situations where Pandoc can be convenient. For example, I wanted a document[1] to be written primarily as README.md (CommonMark format), so that GitHub could render it as the project README. At the same time I wanted to render a PDF output from a customized form of the content. Pandoc is convenient for cases like this although it takes a bit of work to fine-tune the formatting and customize the content for each output format.
