Advantage is of course the large buffer: (at a great distance, vacuum cleaner, extension cable in between) even under less favorable conditions create the equipment abundantly still about 100 Mbit connection over the power grid, so that the 100Mbps network port can be fully exploited.
Two ports are very convenient, you may save a one switch. Also on the feed-in page on the router makes the second connection point, for example, if the router has only one LAN port and you want to connect a PC / printer there.
The power socket is very convenient - especially because it is recommended to use for good reception directly the wall sockets.