My initial tests didn't look very promising and after some back-and-forth with D-Link, I'm even less encouraged. I'll have full details in an upcoming review, but basically I see no sign that the Clear Channel Assessment (CCA) mechanism added in Draft 2.0 is working properly.
Specifically, a Draft 2.0 AP that is in 40 MHz channel mode is supposed to immediately switch to using the legacy-friendly 20 MHz channel mode and stay there for 30 minutes if it detects a device using the extension channel. (For example, for an AP in 40 MHz mode set to Channel 1, the extension channel is 6.) The device in the extension channel doesn't even have to be actively transmitting; beaconing APs or probing STAs should be sufficient to trigger the CCA fallback. Despite repeated attempts, I have yet to see an AP switch from 40 to 20 MHz channel mode with this experiment.
But as the certification and standards-making processes drag on, it looks like few people really care. New draft 11n products continue to appear and consumers buy them ($150M worth to date, according to a recent Dell'Oro Group report) with the main deterrent to purchase being price rather than interoperability or compatibility.
Even the enterprise wireless guys are jumping on the bandwagon, with Meru shipping a two-radio draft 11n AP and controller this summer to be installed at Morrisville State College in upstate New York and Colubris, Trapeze and Ruckus Wireless also announcing draft 11n gear.
So, yeah, big deal, the first Draft 2.0 products still don't work right. As long as D-Link is willing to cut the price enough, they'll sell. It's enough to make me want to stop rigourously testing this stuff, since not many buyers seem to care.