why should one spend hours , first: if affected: you can delete all comments with a couple of mysql command
http://www.cyberciti.biz/faq/wordpre...ql-statements/
in 5 seconds
second:
easiest way to keep your comments clean is to
disable or rename wp-comments-post.php
and disable or rename or protect xmlrpc.php in your .htaccess
that doesnt eat any ressources
of your sever like ip blocking
using ip blocking for those comments spammer is like using a hydrogen bomb for killing ants
ps:
okay , i forgot this of course is only possible if you dont need any comments on your wordpress
if you do , maybe ip blocking makes sense..