Basically, :class:`!Foo` has no advantage over ``Foo``. The no-linking syntax is really only there for completeness, but I would prefer the plainer and easier to read (in source) ``Foo``.

For files, :file: really only has an advantage if you do something with the information that it's a file (which we don't, currently), or if you use the special feature that you can embed variable parts with {}.