Doesn't seem like a real risk - these files are all version controlled.

The bigger problem is you now need custom tooling for your IDE, version control, diff & merge, code review, code hosting, etc. etc.

You're spot-on. HTML and XML are similar textual embedding formats for documents which can contain arbitrary text. Neither is particularly good when the documents are syntax trees though. CSTML takes the design ideas that obviously work and adapts them to be natural for syntax trees, like this: https://gist.github.com/conartist6/75dc969b685bbf69c9fa9800c.... The trees always store inside themselves the complete source code as the parser saw it, so there's little fear of not being able to recover the original, and they're quite human-readable unlike, say, docx files. My team and I are working on building out the VCS, diff and merge, review, hosting, grepping, blogging and other kinds of solutions necessary to make our format able to take over as a de-facto standard.