Design-Build does not necessarily cost more, because each entity carries the same risk as if they were separate (architect and GC). However, with a Design-Build GMP, which is what we typically use on our developments, that costs a premium, but its a cost we can be comfortable with on the front end, so I will (and do!) gladly pay a premium for a guaranteed cost of construction, particularly since the contractor has the significant information advantage on dealing with problem that arise.