The mod is fine and extremely useful however I have a problem with backup and restore.
The PHPBB3 RC4 backup works fine but when restoring from a previous backup file, I always get a SQL syntax error which says:
SQL ERROR [ mysqli ]
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'index, user_id, user_ip, allow_viewonline, last_visit) VALUES (3, 2, '127.0.0.1'' at line 1 
INSERT INTO phpbb3_visitors_today (index, user_id, user_ip, allow_viewonline, last_visit) VALUES (3, 2, '127.0.0.1', 1, 1186730833)
This is on a clean RC4 test installation.