I used to keep JDs and can agree with everything TCTfish says. The larger they get, the more aggressive they become. Things can be going fine and all of a sudden one will go on a killing rampage. So you are best to pick a single pair. That being said, they are still worth keeping.
Being a discus keeper I'm a fan of bare bottom tanks. However, these fish love to dig in gravel. I think they might be happier with a substrate. As long as you do your pwcs and gravel vacs you shouldn't have any problem.
Feeding. Avoid the temptation to feed feeder fish.
IMO, unless you're raising your own, it's the surest way to introduce pathogens into the tank. If the JDs are large enough, whole earthworms are especially relished.