A Ripper can do more than kill mages. My success rate with rippers is still mixed, but I like to flank things with a Ripper Chief. They usually do some decent damage and then get very few attacks back.
I learned a few things the hard way.
First, the unit is usually steadfast so if you beat them by 4 CR it will rarely matter.
Second, if you flank an enemy fairly close to your front lines you can combo charge the flanked unit. If you vanguard forward and closer to the enemy's front lines, someone will flank your Ripper Chief and kill it dead.