So I currently have a previous generation airport extreme and airport express. I'm thinking about buying a new airport extreme to help fill in a few holes in my house. I'd love to use the new one to set up dual-network, and then use my old pieces to extend the "n" part of the dual network around the house. I don't care if the "g" part isn't as strong around the house because it is only for my iPhone. Does this seem possible? I'm wondering if the old pieces will be smart enough to help extend only the "n" network and ignore the "g" network.