Here's something I have tried in the last couple of days. I have Time Capsule and Airport Express. I decided to try the dual band. Time Capsule distributing 802.11n only (5GHz), and in a bridge mode, have Airport Express connected via ethernet, and distribute 802.11g only. Wireless N network has a name "xxxn." Wireless G network has a name "xxxg." Two separate networks are on different frequencies, and are in different radio modes. They are positioned about two feet away from each other. I have used various internet speed test websites, and from a distance close to the routers (same room) I get a speed check of about 25~30 mbps. That's the speed that I'm suppose to get. Move to a couple rooms away, I would say about three wooden walls, a wooden door, some "normal" interfering objects in between. Speed test, and the results are very different. About 20 mbps for Wireless G only network, which is fine. But around 8.5 mbps for Wireless N only in 5GHz. Half the download speed. Upload is same at about 6mbps. In this case, wireless N was slower than wireless G. Harassed an Apple technical support and IP tech friend, and the answer was, "2.4GHz does better at passing through interferences such as large water tanks, electronic devices, glass and metal plates. 5GHz is not as resilient as 2.4GHz. For people experiencing issues with 5GHz, using 2.4GHz might be the better option." So there you go. Performance boost might not be that great. But then again, maybe new device has made a significant improvement.