Fiber is still the most promising high-speed, long-distance networking technology. Mixing network traffic with power distribution is a fundamentally bad idea and it rather surprises me that anyone has even implemented it. It has the same safety margin as, say, changing all the working voltages on a motherboard to plus or minus 240 VDC.
Superimposing a tiny, precise data signal on a huge, imprecise, high-powered power distribution circuit? The whole idea makes me nervous—no thanks. I'll keep the ADSL line.