The collaboration between Motown’s greatest diva and disco’s top auteurs couldn’t have been a bigger hit — but it could have been even better. The version of diana that hit shelves was a compromise — Nile Rodgers and Bernard Edwards’ flourishes were considered “too disco,” and Ross’s voice was too deep in the mix — but both it and the reissued Chic mix are each joyous in their own ways, “Upside Down,” “I’m Coming Out” and all.