Thanks,
I saw the benchmark for Netgear WNR3500L, which has almost the same hardware like Asus RT-N16 (Asus has 128MB RAM, 32 MB flash, Netgear only 64MB RAM, 8MB flash), and WNR3500L throughput is 256/301 Mbps (WAN to LAN / LAN to WAN) with stock firmware. So the probably hardware minimum throughput for Asus should be the same as Netgear one I think.
SNB review for Netgear WNR3500L
SNB review for Asus RT-N16





