I've had mixed results. It absolutely saved one rifle for me. That barrel was one of those anomalies that shot great when it was scrubbed down to bare metal but after 2 groups it started opening up and tossing fliers. It took awhile to figure that out. Crazy Davey put me onto DBC so with little to lose I tried it. It made a night and day difference. After coating, shooting it in and cleaning again it shoots the same clean or dirty and I've gone hundreds of rounds without cleaning. Tempermental to a 700 yard Kimber; that's a deal I can live with.
I did some other barrels that shot pretty good and didn't foul much. After coating they still didn't foul much and shot the same. Maybe you can't fix something that isn't broken?
I did a 30-06 that will build a copper mine in a few shots. No real change on that one. Maybe there's some kinds of broken that can't be fixed?
I did my .458 that fouls heavily with A-Frames although it doesn't affect the way it shoots. It still fouls with A-frames and their soft sticky jacket but is better with everything else. I can shoot a couple of CEBs though it and it takes the fouling out, much like a jacketed bullet will scrape lead out of a barrel. Its kinda neat.
I doubt that any product can be a universal cure-all for everything, but it is a useful trick some of the time. Never seen it hurt anything though. One caution is when cooking in the coating use loads that are backed way off. Pressures go through the ceiling otherwise.