Since the 777 is older, and this has never happened, and they are giving airlines 5 years to make the change, it doesn't seem likely to be an actual problem.
I've been doing that for years, but mainly because I noticed that I sleep by far the best on A350s for long-duration flights (I do Germany-Korea often). Also good but a bit less so was the A380. On Boeing planes I've never been as restful. I suspect it's something about the AC system or the NVH. It seems to hold true across airlines.
There's some amount of piling on around the adjectives being used to describe the issue. There's a problem with Pratt/Whitney engines on the Airbus A320 that could be described in scarier terms than it usually is.
https://en.wikipedia.org/wiki/TWA_Flight_800