performance : load xml file vs query xml field

Does anyone have any benchmarks or general knowledge regarding the performance System.XML 2.0 and SS05 for these two scenarios:

1. XPathDocument xpathdoc = New XPathDocument(pathToXMLFile);

2. storing the contents of the xml file in SS05 ( in a col of XML datatype ) , and using SQLHelper to load it into an xpathdoc
We haven't done such measurements. For case #2, you have a make a roundtrip to the server, which will be more costly than reading from the file, although I cannot say by how much.

I think a fairer comparison is to compare the processing for case #1 with running the query on the XML data type column at the server. XML indexes on the XML column can significantly speed up queries.

Thank you,

Shankar