When working on the release of dbForge Transaction Log, among other tasks, our team had to puzzle out how to properly store typed XML data.
To start with, it is worth mentioning that SQL Server does not store XML in the format it was entered. An XML string is parsed, split to tags, and thus is stored in a compressed format. Description elements that the server considers unnecessary are discarded.
It also should be kept in mind that, if the data type of a column is specified as simple XML, the server will store this data as Unicode strings.
Click through for a couple of examples and their data storage requirements.