Well, if you are using DFS then you have no choice but to use UNC. Generally HTTP provides byte-level checkpoint restart that UNC does not. Also, it is generally less problematic to use HTTP over UNC when it comes to permissions in a multi domain environment.
There is some pretty good info in the LDMS manual starting at page 186 on this - http://landesk.avocent.com/docs/manuals/LDMS88docs_en.zip
Hope this helps...