In only one of those situations is it better than Ghorn.. And you can just use Fatebringer/Icebreaker/Any weapon with Firefly and it's far better than DB.. Seriously, 5 shots of DB into Deathsinger? What do you think 5 Ghorn shots would do? Conclusion: DB is a terrible exotic.. You can try to justify Truth but even that isn't worth it. Ghorn > All.