Not sure what planet you all are living on, but I wouldn't dare put anything in my tank with my armatus unless I wanted it shanked a few times. Theres just no way my guy would accept another mate unless it was way bigger than him.
JD had him in with a massive distichodus and datnoid, and other things, but the smaller peacock in there looked scared ****less. The damn fish even fake bullrushes my hand through the glass, baring his teeth.
Some of the japanese sites show them "cohabbing," but all with very large tankmates, and the armatus look very, very well fed.
You guys know your fish better than I do, and considering I am new to this monster fish/armatus game, you will be fine...but I'll be watching to see what works and what doesn't. I just can't afford a $100.00 feeder, when the armatus will literally poop it out in half a day.