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.