> If you're just after something that's
> cheap and Pi-sized, you'd probably have better luck with something like
> the ODROID C1[0]; you still may not saturate the link though.
From experience, an ODROID box won't help too much. It just doesn't have enough CPU.
For a little over $100 (USD), you can get a tiny box with an Intel chip, with a gigabit ethernet interface, like this one:
It's more straightforward to run standard Linux distributions on this hardware. The Raspberry Pi and ODROID are using ARM or Exynos chipsets; distribution choices are limited and security updates often lag behind. This particular Intel chip doesn't have AES-NI, but I'm running a relay on one of these boxes that averages about 40 Mb/s, and has no problem spiking up to 80 to 120 Mb/s when the load from Tor is higher.
If you want a box with AES-NI and a gigabit ethernet interface, cost starts jumping up to several hundred US dollars or more, so I find the lack of AES-NI to be an acceptable compromise for the value.