I've been looking into alternatives for WP-Filebase and found 3 on CodeCanyon that seem to do the job:
http://codecanyon.net/item/file-manager-plugin-for-wordpress/2640424
http://codecanyon.net/item/groups-file-access-wordpress-plugin/2228793
http://codecanyon.net/item/file-manager/8999688
I haven't gone through the finer details yet but they all seem like viable alternatives overall.