Basically, use the best tool for the job. If you're working with complex data structures from many sources, having data, validation and transformation languages

Basically, use the best tool for the job. If you're working with complex data structures from many sources, having data, validation and transformation languages (XML, XSD and XSLT) which have been co-developed and refined to basically be able to validate any third-party tool is invaluable. Sometimes extra safety is worth both the extra space and time.