They're nasty, but not more nasty than, say; big Julidochromis marlieri, treto's and the like.
BUT in a small tank, they can get downright psychotic, whereas in a big tank, they can get very easy to maintain.
if you have a 400L/100G tank: NO problem.
if you "cram" them in a 55G or smaller: BIG BIG problem.
another trick is to keep them with sturdy fish.
friend of mine has his with Synodontis, Cyathopharynx foai (wich is a nutter), Triglachromis otostigma, trets and Spathodus; no worries.
it's a 135G tank with lots of open water, but a huge rockpile with plenty of PVC-pipe hidden as well.
they also mix well with Tropheus, Petrochromis, Juli's, Chalinochromis etc