I think it's a pretty risky thing to do.
If your intentions are to NOT sell the young you'll get in the tank, then I don't see an issue, otherwise.....
On the other hand if your talking about keeping Paracyprichromis brieni in combination with a Cyprichromis species, I would say 'Why not?'
I'm not sure about a P. nigripinnis - Cyp-combination since the first species is rather timid compared to the other species.
No matter how life brings me down, looking at my beautiful daughter makes everything aaaaaaaaaaaaaalright! :D