A design done by an independent architect would allow you to get bids from more than one builder. That would seem to be the smart move to make.
But Design/Build provides a system that guarantees the design will meet your budget. Because your Dakota Dawn Design/Build architect knows what the pieces cost, he can assemble a design the meets your needs without busting the budget.
And, Dakota Dawn allows you to get those outside prices as well if you want.
DB vs Arch