chromatic in some ways I agree with your view of not using XML for configuration files. If I have simple data then I don't. If I have a simple set of data then I would just go and use AppConfig or some other equivalent.

However when you have highly structured data it becomes a really difficult proposition to make the config files readable anyway since you may want to make it refer to itself in some way, or have some arbitrary nesting of configuration options.

So, out of interest, do you think you should never under any circumstances use XML for configuration files? Or what?