Tom Doak,
I'm with Nigel; can you educate us on why double greens and fairways might hold a course back? I can see two concerns, one being slower play if the greens and fairways are too small or narrow, the other being potentially greater liability due to the enhanced possibility of injury because of the closer proximity of players to each other. Are there other factors as well?
If the site is large enough, I can see how these problems could be reduced. Of course, that might require larger areas that would have to be shaped, built out, and grassed. They would then have to be maintained and watered too.