The iGTD to Omnifocus importer should now handle archived items correctly, creating an archive category tree, with the tasks attached to each category, in a separate date-stamped archive folder in Omnifocus. The top-level categories are Omnifocus projects, with their status set to "on hold".

The current draft is at

http://web.mac.com/robinfrancistrew/...Omnifocus.html

(The previous version was placing archived items in the inbox, stirring memories of the myth of Sisyphus).