Take it to the max...
Since there are two radios, and given the throughput results above, I should be able to get a best case 29Mbps average throughput from the 11a radio in Turbo mode, plus 19Mbps from the 11g radio for a total of 48Mbps aggregate throughput, right? Check out Figure 24 to see what really happens when both radios are loaded to the max.
Figure 24: Maximim bandwidth test
(click on the image for a full-sized view)
This test took actually ran the WAG511 in 11g mode first, then kicked in the WAB501 set to 11a normal mode, ran both for awhile, then let the WAB501 finish by itself. Since four separate computers were used, any bottlenecks would have to come from the FWAG, since it's the only common element in the test.
You can see that when the WAB501 kicks in, both cards average about 15Mbps, for an aggregate throughput of about 30Mbps - almost 40% below the 48Mbps that I calculated from individual tests. I'm not sure whether this will be able to be improved via a firmware update, or an upgrade to a processor with more oomph will be required. At any rate, if you see any "starbursts" on WLAN product boxes claiming "over 200Mbps speed!" (which I'd think someone would try on a dual-radio AP or router that supported both 11a Turbo and one of the 11g speed-boosting technologies) I'd treat it with a very skeptical eye!