I see a number of LFS where Tilapia Buttikofferi are sold in smaller sizes either mixed with Malawi Cichlids or with Oscars and Dempseys.
As a West African cichlid they grow to be large (I've read online "up to 14 inches") and they are aggressive to the point of being nasty.
I don't know how they'd do with Dempseys et al at home, but I had a pair of juvies when they were first imported in the mid-80s and they were being presented as Malawian. They were in a tank with juvie Mbuna, and over a 3-month period they gradually outgrew their tankmates.
Then they started to bully them. Then they started to terrorize them. Then they went back to the LFS!
They're gorgeous fish, and I've seen some striking 8" specimens in stores (they're now common around here), but they call for large tanks, good filtration, and burly neighbors.
I don't see these guys around here often at all. I've never had them before but I think they are awesome looking fish. I had some polystigma's given to me roughly 7 months ago 1 male 2 females, they were hyper aggressive so I traded them in to a LFS. the owner was thrilled when I brought them in he said they never get adult females brought in, and I gave him a trio. I seen this guy last week and he said some one bought them the same day and now they have produced many fry..
from what I have heard the buttikofferi is basically a fish to be left by themselves, I could not imagine what they would do to a dempsey. that I think would not be pretty.