Wireless Performance - 3 Stream, 2.4 GHz, Closing Thoughts
To compare three-stream 2.4 GHz performance, we need to use two other routers, TRENDnet's TEW-691GR and D-Link's DIR-665. Figure 15 shows 20 MHz mode downlink performance with the Gen 5 falling between the other two at all test locations.
Figure 15: Radar plot comparison, 2.4 GHz, 3 stream, 20 MHz mode, downstream
As is usually the case, Figure 16 presents a different view, with the AirPort Extreme beating both the TRENDnet and D-Link at all test locations!
Figure 16: Radar plot comparison, 2.4 GHz, 3 stream, 20 MHz mode, upstream
Figure 17 shows the 2.4 GHz three-stream IxChariot downlink plot.
Figure 17: Apple AirPort Extreme 5th Gen IxChariot summary - 3 stream 2.4 GHz, 20 MHz mode, downlink
Here are links to the other three-stream 2.4 GHz plots for your reference:
There has been considerable buzz around the Gen 5, mainly due to the higher transmit power that forum denizens uncovered by parsing the FCC test reports. But higher transmit power on a router or AP doesn't really help if the client doesn't have equivalent power to communicate back. And so it is with the AirPort Extreme Gen 5.
The bottom line is that the AirPort Extreme Gen 5 definitely has improved throughput for medium to low signal levels in 2.4 GHz. But any performance gains in the 5 GHz side are offset by losses in other test locations and directions (up / downlink).
In other words, the Gen 5 is likely to perform better in the 2.4 GHz band where the Gen 4 doesn't. But in the 5 GHz band, you might see a slight performance improvement, but it's just as likely you won't.
Updated 8/25/11: Clarified cost comments
If you've been hoping that Apple has sprinkled the same fairy dust into AirPort Extreme Gen 5 that it uses on its tablets and phones to make it the über-router to solve all your wireless performance problems, it hasn't. It's just yet-another simultaneous dual-band N router that some people will rave about and others will rave at. And certainly not worth paying
the top-dollar that Apple is customarily charging $30 or so extra.