Mine is, in theory, 2Gb/s. In practise, nearer 50Mb/s.

It also causes interference on my amplifier, although it's a cheap amplifier.

About once a year one of the adaptors loses its connection to the other adaptor, and instead connects to someone else's setup in this apartment building.

I had a similar issue until I limited the amount of wire between the connections. For example I put one right by an outlet under my breaker box, then another in my garage right where the subpanel is and it improved dramatically.

Aside from the terrible and inconsistent performance, the bigger problem is the sheer amount of electrical noise introduced into the line which can adversely affect electrical appliances and devices.

Personally, I just don't find all the drawbacks worth it.

Same. It was great 10 years ago, but wifi speeds at this point make the wired through electric lines painfully slow. Even with the occasional wifi hiccup, wifi is almost always better.

it's been 10 years but I had great success running internet into the basement this way. Wifi was terrible down there (router was in the upper floor) and there wasn't an existing ethernet cable going down. Of course it wasn't perfect but it was trivial to set up and worked.