When I repeated my throughput tests with Super-G enabled, things got a little more interesting.

The setup summary:

Figure 22 shows that the Super-G WLAN pretty much shuts down the 11g WLAN, with little disturbance to the Super-G WLAN itself.

Things improve a little at 30 feet (Figure 23), but the 11g WLAN still doesn't get much air time.

Finally, at 50 feet, the 11g WLAN starts to get some wind back into its sails (Figure 24). But it's still significantly slowed by the Super-G WLAN running full blast.

By the way, the drop in Super-G throughput around the 55 second mark is not due to interaction between the Super-G and 11g WLANs, but instead to part of dynamic Super-G's algorithms. It appears that even if a dynamic Super-G AP doesn't detect "normal" 11g or 11b clients in range, it will fall back to normal 11g on a periodic basis.

The timing appeared to be 45 seconds of Super-G and 15 seconds of 11g in the NETGEAR BETA dynamic Super-G updates that I used. A different implementation of dynamic Super-G in D-Link Super-G enabled gear used by Broadcom in its testing showed the timing to be 120 seconds of Super-G and 75 seconds of 11g. So it looks like Atheros, NETGEAR, or both are doing some performance tuning.

Conclusion:
A Super-G wireless LAN running at full speed will interfere with an 11g WLAN also running at full speed. Severe throughput loss in the 11g WLAN can occur up to 30 feet away and significant throughput loss may still be seen around 50 feet.

Figure 22: Throughput for Atheros Super-G vs Broadcom 11g - 10ft
(click on the image for a full-sized view)

Figure 23: Throughput for Atheros Super-G vs Broadcom 11g - 30ft
(click on the image for a full-sized view)

Figure 24: Throughput for Atheros Super-G vs Broadcom 11g - 50ft
(click on the image for a full-sized view)