> My formative experience of their backwards compatibility was being unable to open old word docs in newer versions of word. From experience: Word's still drop

> My formative experience of their backwards compatibility was being unable to open old word docs in newer versions of word. From experience: Word's still dropping support for older documents, and LibreOffice still supports them. (The only LO incompatibility I know is missing Math formulae sometimes, and that might have been fixed; if not, it's a fairly straightforward code change, since OOXML Math tags contain textboxes.)