I actually think having its own set of gear is more beneficial than sharing with the other healers. Here's why:

Endgame gear is almost all unique, meaning you can only have one of each piece. For BiS sets, you'll be melding materia on these unique pieces of gear. Most endgame healers meld accuracy to avoid missing their dps, and compliment that with something like piety. Because Dancer would rely a lot more on accuracy, since Drain Samba requires DPSing to heal, accuracy should be built into their gear so that Dancers don't feel like they must meld accuracy in order to avoid healing loss. By having their own set of gear, players don't have to choose between an optimal Dancer set vs an optimal WHM/SCH/AST set.