Interesting. I will leave the catfish with the mbuna then. Even though the cats are Tangyanikan and the mbuna are malawi, it's a combo that seems to work great. And if I'm stripping the females before they spit the fry, I shouldn't lose any to the catfish.
As far as the hecqui, they're doing fine by themselves in a 24x12 15g tank. So they can stay there if needed.
I was originally thinking hecqui + leleupi because many people seem to think they are meaner/more aggressive species and could effectively compete with each other. On the other hand, my leleupi seem to be getting along great in my 36x12 with much smaller julies, even hiding in the same rocks. But neither species is breeding at the moment, so I will continue to monitor things.
I suppose I could try the hecqui, leleupi, and julies, and then if that didn't work, try another shelldweller, e.g. ocellatus, in place of the hecqui. But that might not work well for keeping any fry, if the ocellatus are bad parents.
If I was only doing three species, I could just leave the leleupi and julies in the 36x12 and wait on the cyps. I'll continue to do some research...maybe try sticking the hecqui in with the julies and leleupi in the 36x12 on a Saturday when I can watch them closely and see how they react to each other. And put in a divider if there are issues or move them back out.