I've kept common Plecos in Mbuna tanks.....only because I had no other place to keep them after they got to big. To be honest, I'm not sure what the purpose of keeping hypostomus punctatus (common pleco) is......they aren't nearly as attractive as the rarer spotted types, they grow absurdly large, they don't scavange that well, etc. Different strokes I guess.
The specimen I had in the Mbuna tank was about 8", and even though well armored he took an absurd amount of abuse. The favorite rock he liked to hide out under was shared with a 6" Pindanni, and the Pindanni spent a good deal of effort trying to dislodge him. The African would grab the pectoral fins of the pleco and viciously try to yank him off the rock he was suckered to, and just relentlessly attack him. After the Pleco gave in and moved to a different rock the attacks stopped.
I guess if your African tank has enough diffused aggresion and plenty of spots for the Pleco to hide he'll do OK.
Should be no problem in a any South American tank. Even full grown Dempseys, Jewels and Green Terrors aren't a fraction as psycho as even a mild Mbuna tank.