"Per-developer visual indent width" feels like the strongest argument for using tabs on a project, as virtually all editors let you choose the visual tab width.

"Per-developer visual indent width" feels like the strongest argument for using tabs on a project, as virtually all editors let you choose the visual tab width. That said, the visual indent width seems like something that ought to be solved with editor software regardless of the tab type. Editors already transparently solve many problems with indentation (e.g. automatically detect the indentation type, indent x spaces when you press tab, continue indent on newline, unindent when you type a closing brace, etc). Good editor support for indent width preferences would help folks comfortably work on any project regardless of its indentation type. And as a side note, it would be nice to reserve big ol' wide tabs for tabular data. Using them as logical indentation feels a bit like a shoehorn.