Thanks for all the inputs. I have somewhere read about "somebodies" share a whole Access-DB via Dropbox. Of course everyone works temporarily on own copy, but if read only is required, it might still be OK. I was just wandering what happens if /or Dropbox attempts to start syncing after someone else made changes, and the db is open.
The idea was of course to have a simple very limited tool for sharing, without VPN or other measures that are beyond a huge number of users.
But it seems it might not be the way to go.