Thanks - that was the information I wanted!
Since all of the servers have the same licenses, BES Platform and ILMT, I only have to do the gather step once!
Another tip for you who are using the non-extracting mode:
You can use sqlite3 to examine the content of Airgap.db and AirgapCache.db.
E.g. this command to see the versions of the external sites:
sqlite3 Airgap.db "select siteid,sitename,version from sites"