It's depends a lot on you house and the how its wired up into the breaker system. These are actually slower than wireless 802.11ac I gave this a try before I got my iMac
I have a 1gb up and down connection that I can max out when I connect two gigabyte lan cords from my router to my Mac Pro. When I only connect 1 cord I seem to max out around 800mbps. I'm not sure why that's is.
I also have a late 2013 iMac (fully maxed out) with the new AC card inside of it (the apple 3 antennas version) I get a full 1300mbps connection when I'm 20 feet away. Although when I download I maxed out around 650mbps. So I wired up a cord to my 1 gigabyte connection and I still max out at 650-700mbps on my iMac through the cord (20 foot) but with a shorter 10 foot cord I was able to reach 980mbps speed tests (maybe my longer cord is bad)
Those adapters run at a max of 500mbps (rated) and they are actually a lot slower since it depends on your houses wiring. I used to use this when I had Comcast a few years ago at my old house and it was rated for 500mbps but I could only connect at 100-200mbps. I even tried with a very close power socket.
If you have internet that is 100mbps or less then yes your method will work just fine. If you have a very fast connection like me you just gimping yourself with that device. My iMac connects at 1300mbps from 20 feet away. This is really good for the distance, but I'm sure their is some packet loss (like all wireless) which is why I can't seem to go over 650mbps on speed tests or when downloading wirelessly.
Seems there is always some atypical user (you) with some atypical scenario (maxing out 1GB up/down internet) who can say something like Powerline isn't perfect. In reality, most people have less than 100mbps internet in their homes, and I would guess for most people, their house wiring is just fine and having a wired connection works better than dealing with the issues of WIFI most of the time, especially when you are further that 20 feet and many walls away from your wifi router. Many homes / apartments have huge congestion issues with WIFI, and suffer poor performance (in reference to your claim that house wiring *could* be a problem).
Not really sure what you're doing maxing out 1Gbps broadband connections, but I'd go out on a limb and say 200-500mbps is fine more most people and for $40, a great solution.
My experience with Powerline is very good. The only time it would not work is in giant homes/buildings separated by separate electrical panels.
But, in your case, I'm happy that your "ac" wifi is working for you.
