Migrating SWFUpload field to Drupal 7 Field

I recently tried to migrate a D6 site with SWFUpload to D7 / regular fields using the CCK module for migrating field content. Here's what I learned:

• There's no migrating without manually changing a couple of things in the D6 field descriptor tables, the fields describing the name of the widget and the name of the imagefield.
• After changing the values of the SWFUpload field to match a generic filefield/imagefield, the migration assistant did it's job but the contents still didn't show up. It created the field as a D7 field and migrated settings, but the images which habe been uplaoded didn't appear as field items.
• In retrospect, I should have deactivated the widget on the filefiled *before* upgrading the D6 codebase. Maybe this would have solved the issue?

At the end I was faster reuploading the images one by one than figuring out a working migration procedure. :-) Now I'm about to do another migration and I'd love to know wether anyone already figured out a painless and working procedure.