This is my assessment of Double Edge Dance, etc:
The standard Side B input is the best for closing out stocks near the edge, as it has the best launch, and good damage.
The up tilted variant sets up combos into SH Up Air, U Tilt, and Up B. It can also chain into Jab and F Smash at lower percents, although they can use Double Jump to avoid the F Smash at percents near 40. It also covers the space above Roy for certain characters who see DED coming and try to jump over it.
The down tilted version does the most damage (17-20% if all hits connect), has the most horizontal reach, and can double as a shield poke when the opponents shield is unhealthy. In short, it's the best option for shiled pressuring from a safe distance, and functions as a solid damage rack.
I've found that the best uses of each are situational, and when in doubt, just go for the side B version, since the launch pretty much guarentess you will maintain stage control.
Also keep in mind, DED is NOT safe on shield at all, but sometimes you can fake them into dropping shield by delaying your next input between DED2 and 3, and also hitting with the Sweetspot VS an unhealthy shield can sometimes still result in a shield poke, which can occasionally net you unexpected kills near the edge, but this is risky as hell.