Your comment above (which has disappeared) adds a logging call ("Did not copy Category field to Level field") every time a presentation is added. Is this necessary? When importing a talk csv/rss file, there is quite a bit of debug output.

        try:
            if not presentation.level and presentation.category:
                presentation.level = presentation.category
        except AttributeError:
            log.debug("Did not copy Category field to Level field")