GT's Rule!!!!
I have a mated pair of JD's that never get out of their flower pot, except to lunge at somebody going by.
My GT pair are always out partying, will eat anything, and are much more colorfull.
I used to have an 8" GT I got from the LFS. Someone had brought him in because he had killed everyting in his community tank. I kept him in a 75 Gal by himself until I got a new 180 gal and thoght with the extra room he would be OK. Wrong, he took my 12" oscar by the mouth and drug him around the tank then began ramming him in the side untul I could get him out. Some GT's are mellow, it depends on the individual fish, but I never met one that could not hold his own. If you want a good looking bad ass GT is the man.