Yes, we use XML in my company with some complex schemas. But since the beginning we have used LiquidXML to define the schema and generate the code (C++ and C#), otherwise it would have been a nightmare. But I must admit that it works fine: the process is quick, we can easily manage versioning and performances are good. But don't look at the generated code, it's awful! In the last developments, we now use Json (manually) but the data structures are less complex so it's not really comparable.