DB-DC is the straight business for attacking. Count me as one of the people who believe Dragonite's new movesets constitute a nerf to his overall ability as a gym sweeper.
IF you don't want to use up your candies on this beast you can always wait for trading. Many guys like myself have extra DB-DC we would be willing to trade. I've got many I never use actually
here is a video I just saw comparing DB-DC to DT-OR and DT-H:
https://www.youtube.com/watch?v=GnOj8TyygOU
The video basically shows that DT-OR provides the highest cycle DPS of any moveset for Dragonite; however, the final battle against Snorlax illustrates, quite clearly I think, that DB-DC is still a better sweeper (for taking out multiple pokemon because of effective dodging).