I've been using Sea Foam for about two years. I used it to clean a carbon ring out in my 6.5-284 Norma, with lots of elbow grease. After that ordeal, I started include it as part of my regular cleaning routine. Ring has not returned, yet.
Just picked up a bottle of Break Free CAC Carbon Cutter. Thought I'd give it a try, so can't say what it will/won't do.