Maybe something like the following could be a good compromise?
<resource raw="false" content-type="application/xml" modified-date="2012-02-02T19:13:42.000Z" name="file.xml"> <property name="prop1">value1</property> <property name="prop2">value2</property>
</resource>
Funny, I also thought about this solution.. One advantage would be that we could use arbitrary strings as keys. However, it would make the output incompatible to previous versions (..unless we use another function for it).
More suggestions are welcome, C.