[eluser]gtech[/eluser]
I use triggers in MYSQL and they work fine.. the added advantage of using the database trigger is that it gets fired even when data is modified using the MYSQL CLI, as you probably are aware.
If your just after rollbacks then transactions work well in CodeIgniter, (db_debug has to be set to FALSE in the config/database.php file).. be sure to set the table types as innodb.
if you use a transaction you can also check to see if a transaction was unsuccessful/successful and call the relevant function.
However I am unaware of a method that allows you to call a CI controller/model function when a database trigger is activated.