I hate high rate data links over power lines. Power lines are not impedance controlled. At every bend, every approach to some metal in the building, they are going to radiate interference and accept/receive interference from their environment. Using powerline networking is irresponsible and rude. The fact that any are approved by the FCC at all is entirely due to contrived testing setups that are never replicated in real building wiring.
If you use real transmission line like ethernet cable (~70 ohm twisted pairs) or coax the impedance remains constant and they might even have a bit of shielding. You'll get faster, more reliable speeds and pollute the radio spectrum significantly less.
- It's fiddly and ugly compared to hidden cables. I wouldn't do that in my own home, I'd run them in the walls.
- It's disruptive and time consuming. It would likely take me a whole day
- I don't see why I should invest further in improving the property when I will likely move out in 1-2 years time and won't reap the long-term benefits. I've done that already in other areas.
- It's hassle. My landlord could protest that I've done a shitty job when I move out, or, even if I haven't, make me remove it.
- I need multiple WiFi adapters anyway to cover both upstairs and downstairs effectively.
- It's not as flexible (in terms of moving things around) as plugging an adapter in to any electrical outlet.
- I needed a quick solution when I moved in so I could work.
Your country almost certainly has rules about emissions in the HF frequency ranges too. Even milliwatts of radiated interference at these low frequencies will bounce around the world and interfere with everyone.
If you use real transmission line like ethernet cable (~70 ohm twisted pairs) or coax the impedance remains constant and they might even have a bit of shielding. You'll get faster, more reliable speeds and pollute the radio spectrum significantly less.