I haven't tried it, but I think the constant movement of all the pbass and there agressive eating habbits would really stress the discus out. IMO I wouldn't do it.
The peacock bass will destroy the discus. IMO the peacocks will eat kill them in a couple days tops unless the tank is just absolutely huge and there is a ton of swimming space, I suppose its possible; I've seen discus kept with stingrays and arowanas so who knows... Wouldn't recommend it though unless you don't mind losing the discus ~Trent
I don't aggression is a problem but more of the discus not getting enough food.