Actually, as written, Deific Obedience gives you Exalted Boons if you don't have levels in a PrC that grants divine boons. The moment you pick up one of the PrC's that grant divine boons, you get those instead. Deific Obedience does not say that you can only get boons of one type, only that it replaces the default boons with specific boons. There is no wording that I have found that says you can only have one set of divine boons, or that precludes you from gaining multiple sets of boons. I would love to see the text that says otherwise, because I have been searching for a while.