So yes the absolute path works fine and I amended the opening post.
If the wedge database user does not have permission to the smf database then the following message is given:
Sorry, the database connection information used in the specified installation of Wedge cannot access the installation of %1. This may either mean that the installation doesn't exist, or that the MySQL account used does not have permissions to access it.
The error MySQL gave was: 'SELECT command denied to user 'wedgeuser'@'localhost' for table 'smf_members'
Obviously the importer works if the SELECT premission is given to the wedge user on the smf database.
If the wedge database user does not have permission to the smf database then the following message is given:
Sorry, the database connection information used in the specified installation of Wedge cannot access the installation of %1. This may either mean that the installation doesn't exist, or that the MySQL account used does not have permissions to access it.
The error MySQL gave was: 'SELECT command denied to user 'wedgeuser'@'localhost' for table 'smf_members'
Obviously the importer works if the SELECT premission is given to the wedge user on the smf database.