They make very good community fish, I got mine around the 6" mark.
Its a male albino GG, he absolutely hates silver coloured fish and will harass them. He also has a problem with my chocolate cichlid, but because I have a large tank that is 3 feet wide he has never bullied fish beyond just a small chase. They are very intelligent and personal fish. I keep mine in a 225 with a clown knife, 3 bichirs, 2 large tinfoil barbs, a chocolate cichlid, florida gar, large common pleco, and an achara catfish. this is a community of predatory larger fish and I have absolutely no trouble and have been fine with this selection for the last 8 months.
My GG never ever targets anything small. I put feeders in for my florida gar and the chocolate cichlid always kills them but the gar shows no interest. they are intelligent and he knows his food is coming in pellet form so he doesn't even waste the effort to kill a feeder. SO i imagine you could keep one in a community setting with fast robust fish, but also bare in mind that my florida gar is a fragile fish and the gourami completely ignores its existance. So yeah they make pretty good community residents especially when they are above 15". Mines currently around 12"-13" and hes actually pretty mellow besides the occasional chase, but the tinfoils are way too fast to even be bothered by his chasing.