Xml stored as varbinary
If your RDBMS has an xml datatype, why would you not use it?

For example, in SQL Server, you should put XML data in an xml column, because:


The XML data can be compared to an XML Schema Collection, to give the functionality of typed XML.
The XML data can be shredded with XQuery later.
The XML data can be indexed with a number of different XML index types, which help the XQuery shredding.


As far as I can see, the only reason to use varbinary(max) over xml is if you expect to be putting more than 2GB of data into one field. (Of course, there may be other reasons, which I'm sure I'll learn from the posts here. :-).