Yeah, I have paired a 4" clarkii with a CB 3/4" clarkii that I picked up from a friend who was breeding them. In the first hour not only was she swimming peacefully with him but another fish pecked at him and she tore it a new one.
The other pro to getting a CB one is that there's less probability that they will come with a disease.... particularly if you know a local breeder. The fewer tanks it sees before it gets to you, the better.