I have just installed this FW and it seems to work fine.
ASUS WL-500W firmware in English/simple Chinese/traditional Chinese/German/Kroean
1.The version is for 802.11n standard upgrade only
2.Recommend upgrade firmware by wired connection.
I think the reason for this new FW version is to make the router fully 802.11n compliant.
The router is only draft 802.11n from Asus, because it was made before 802.11n ratified. But now 802.11n has been ratified, so I think this FW was made to make the router full 802.11n compliant.
Asus offered a money back guarantee if the router would not be made fully 802.11n compliant after the standard was ratified.