Also, I'd say that the notions of "10x" or "20x" greater productivity from the best developers are set on the wrong footing entirely. Such ideas presuppose that development is just production work, when in reality it is highly creative. The advantage of good developers isn't just that they do what others would do but more efficiently, the advantage is that they do much more. Often times they expand your business. Quite often the genesis of a multi-million dollar product or services offering doesn't come from the top-down, conceived in management and merely implemented by the rank and file, but instead comes from the bottom-up, from a wacky idea that a developer has and rolls into a tech demo. Without great developers that's the sort of thing you miss out on.