Re: Hasn't this been done (better) before?
They ARE cool (I have two) but, if I've understood it correctly, this configuration would solve one major problem the those (or any) repeaters. With repeaters, your device sees it as another wifi network that just happens to have the same SSID and security as the original Which is fine for static devices but a real PITA for laptops, tablets, phones etc. If I have my laptop in the living room it will attach to the homeplug WiFi extender - fine. If I then wander down to the other end of the house, it can still JUST ABOUT hold onto that signal - which it does, even if the signal is so poor that bandwidth is abysmal and even though it is now within 3m of the original router! I have to manually switch it over (or, actually, just hit the function key that toggles WiFi off and on again. When it switches back on it connects to the strongest signal).
A mesh doesn't have that problem as the device only sees one network and the mesh devices sort out all the complicated handover stuff in the same way a mobile phone network does.