I have been running it here for maybe a year now, mainly for the gaming consoles. Interference can be a big problem, but manageable. Big problem is power supplies, power bricks, really. The factory ones for laptops are fine. But aftermarket ones, the cheap Chinese ones, they kill it. Small brick adapters for USB power for smartphones, same thing.
But once you know which ones cause interference, its a simple matter to just not pug those in when you need the connection active. We see speeds of 3.5mbps download, and 1.4mpbs upload normally, and my house was built in 56 and has a hodge podge of wiring. You can also buy filter adapters for plugging in "noisy" items, but I have not tested those
Overall, I am very happy with the system. I only ran one box until recently, when I purchased two refurbished units from Ebay, both of which work great. If I need high speed in another room, I just toss a box in and plug in an ethernet cord. Really handy