Do you put anything under the clamp on the carbon to protect it? In the past I've tightened brakes on MTB handle bars to much and wrecked them so I'm wondering.
Carbon compound can definitely help. As the following link points out, it helps you avoid 'over torquing' to ensure that the component doesn't slip.
In my personal domain, if there is carbon and carbon, or carbon and some other material, thou must use fiber grip. And a torque wrench. No questions.