I use it.
I also happen to be an ex-Signals RF engineer and old RF hand from Motorola (many of us went that way in the civvie street) with a whole shitload of diagnostics kit in the cupboard under the stairs, which I used on first installation (about two years back) to try to determine if the FUD that neckbeards with HAM licenses continually spew about powerline kit was true.
To the absolute best of my diagnostic abilities (and those are still pretty good), the Devolo 200Mb/s kit I have installed does not overspill into any nearby waveband. It's not affecting SW, MW or UHF, ADSL is clear, regular HAM frequencies seem (it's never easy to tell due to environmental factors) to be identical with and without the kit in operation. And by "in operation" I don't just mean "switched on", I mean "plugged in at all". I get more (a lot more, actually) readings from the microwave than I do from the powerline kit.
I have yet to test any other manufacturer's kit but am happy to do so if it's supplied (I will of course return it). In the meantime, if the doomsayers could just shut up and point out any kit they think is flaky, I might be able to get test hardware and find out.