tahta perfect tank! don't listen to anybody, if they aren't fighting they are fine. Plus they won't breed when they are that crowded becasue they have a sense of how much room is left in teh tank. (I just got back from an aquarium with 4000 gallons and the red devils slowed down their breeding because they sorta knew they were running out of space)
Just goes to show that just because some fish had a bad rapp doesn't always mean they all do. Different fish, different personalities.
But I also agree that less ornaments, all males and large group of fish will allow for less aggro.
I have 3 RD's in a 125. Recently 2 of them paired up. They dont like the 3rd coming anywhere near their nesting spot. Luckily he keeps to himself and avoids the pair so there hasnt been any major fighting yet. Nice looking males, keep up the good work and hopefully all stays peaceful.
I am attempting something similar in my 75 gallon- Three decent sized male fish (red texas, freddy, and N. tetracanthus) with some male convicts as targets.