Experience first hand. We decided to make some changes and decided that we should do a full export and according to docs I could do that as an Admin from the Admin settings so I went there and exported everything... or so we thought... Export from Admin only exports what the admin can see so a board where I wasn't involved simply disappeared in the export. I would suggest that if Admin wants to export everything it needs to be everything that is part of the workspace even if the admin can see it or not. Or the Export function needs to clearly state "Export everything you can see"