Regarding low power devices (although not as low power as you guys work on) I have an AMD GX-420CA SoC with 16Gb of RAM right now running pfSense as my home firewall, it works awesome and for a home firewall setup I found that it's actually a bit too much because even when I'm pushing on the downloads and uploads the CPU usage doesn't even reach 30%. Maybe one day when internet speeds really switch gears, like in some cities where Google provides 1Gbps speed, then it will be actually put to heavy use.

I am also working on getting my AMD R-464L as my handmade Media Center machine, I've been procrastinating on it for a long time, but I'm planning to load it with OpenELEC and 4 or 8Gb or RAM. In theory that CPU should be able to handle a lot of processing, even on h264 and h265 at 1080p or higher, but I am still to test that once I get off my lazy butt and get it done.

I've seen that AMD has refreshed both G-Series and R-Series with new CPUs since then, but I'm guessing the performance difference is minimal for the usage I put them through so no need to upgrade any time soon. I will however keep an eye out when they refresh them with new 14nm parts, probably sometime 2017 or even later. Those will really make a difference in power draw and heat.