Hi,
Since I don't have a real answer and sort of must say the same as Anthony (acg) for theories, I found another way of rejecting it (now I'm rid of the "problem") :
It is unncessary slow.
So notice that we are (or I am) used to 1Gb/s of Ethernet speed. This is raw speed, meaning : reality, because I avoid switches or routers (direct PC-PC (PC-NAS) connection).
At this speed and further proper set up in XXHighEnd of diverse parameters (like the necessity of a RAMDisk) you won't notice speed differences with the Ethernet connection vs the usage of an internal SATAIII-speed HDD (SSD).
Ethernet over Power is at best half of that speed, but count on 10% of it. Now also count on the loading of an album (for Unattended) of 30 seconds instead of 3 seconds.
Problem solved (hence don't do it).
http://www.pcadvisor.co.uk/feature/network-wifi/what-is-powerline-3491484/Peter