Using Rules to perform Node Export
The Node Export tab points to a link, so I was able to get this working by setting 'Actions' to 'Page redirect', and pointing it to the page that the Node Export tab points to, a page within the node called 'node_export', e.g. '../node/1602/node_export', where '1602' is the node id (nid). So I entered 'node/[node:nid]/node_export' as the Value of the URL to which it is to be redirected. I also left 'Force redirect' checked. Now when I click the Save button it performs the node export to XML after updating.