Two feats for a single +2 ability bonus seems pretty expensive compared to the DD's bonus.  The DD's ac bonus stacks with enchancement bonuses, and the Stat bonuses also stack with enchancement bonuses. If I REALLY want to wrestle Dragons, I'm going to have to consider that PrC, (or another, perhaps the Greenstar Adept... as gaining class features from that class without gaining the negatives of the class make it very attractive as a choice for a melee type.)