If you care about interference ethernet over power is awful. It basically turns all of your electrical wires into a giant antenna and broadcasts that as broadband noise over multiple miles.
The only reason the things aren't outright banned is the frequencies tend to be sub 100mhz so it only has a significant impact on HF. Still, nasty things and many have been found over the legal noise limits.
If you can I recommend point to point 2.4ghz wifi links. Since wifi is regulated by ERP they have a high gain antenna that usually punches through things better than an omni AP. I've done them through multiple walls from 300-400ft away.
That certainly sounds reasonable. I've poked around with an SDR though, and the only egregiously noisy thing I've seen is the one 100Mbps Ethernet link from the DSL modem to the router.
Before I ran cat6, I indeed used WDS wifi. It wasn't reliable, though, and the particular hardware I had suffered from a bottleneck somewhere that seemed to limit throughout to 6Mbps or so. I could have spent another $500 on less crappy equipment and maybe made it work, but moving to wires everywhere I could was highly effective.
The only reason the things aren't outright banned is the frequencies tend to be sub 100mhz so it only has a significant impact on HF. Still, nasty things and many have been found over the legal noise limits.
If you can I recommend point to point 2.4ghz wifi links. Since wifi is regulated by ERP they have a high gain antenna that usually punches through things better than an omni AP. I've done them through multiple walls from 300-400ft away.