Alternatively, I ordered the ASUS N66U to operate it with asuswrt merlin or DD-WRT.
asuswrt-Merlin turned out to be absolutely stable and user-friendly. they also had all the features I was looking for: OpenVPN, QoS, BitTorrent Client, NAS etc.
also the hardware is really cool: 32MB flash memory, 256MB RAM, 600 MHz CPU.
hopefully it keeps 5-10 years)