Totalxbox.com (The website for the Official Xbox Magazine) has an article discussing the DLC strategy Bungie is using for Destiny, described by Jonty Barnes. Go give it a read.

Short version: DLC does not give a power advantage, but it does provide a larger breadth of gear that the non-DLC crew can see.
Bungie can make updates for balance and changes with minimal disruption due to a better back end.

If we need the DLC to go into Seraphim Vault, an area which is modeled and was even in the beta, I will be quite sad.

If we need the DLC to go into Seraphim Vault, an area which is modeled and was even in the beta, I will be quite sad.

One visit to Google later, thanks for mentioning that--was not aware someone had made it inside that curious door.

I don't think you'll be sad--it'd be odd for Bungie to have the 2nd DLC already on disc.

Wonder how accurate the 'not more powerful items' part will be. Separate but equal is a tough thing to do.