Thanks for the link > See http://drupal.org/node/366464.
Fiddling with http://api.drupal.org/api/function/conf_path/7 is off course a solution but it misses the 'it works out of the box' wish. But maybe I'm just too lazy ;) I now use sites/default/files more and skip the multi site option for making staging more workable. Production is not always under control ie when having a NFS mounted files directory improper sym linked.
