Hello,
on every test I've done so far it's managed 700mbps in both directions, sometimes over 800.
http://beta.speedtest.net/result...
Important: you have to activate "Offloading" so that the NAT functions are executed hardware-accelerated. For this you have to have a current firmware installed (I think at least 1.8.5.) and I had to activate this via command line.
Also, you must not use the device as a switch, because switch functions are executed in software and thus fully utilise the CPU. This is then also at the expense of the routing functions.