My only concern with this would be the 20 minutes to switch to the back-up system, though it might be a slow switch is the safest way to do it if you have time. A system that never has failures is just not going to happen and system downtime of an hour of degraded function one time in a couple of years doesn't seem unreasonable.
If Ryanair's running so tight they can't pick up passengers from a delayed flight for three days, and is too cheap to book them alternative flights, then it's in their interests to stage a song-and-dance for the media claiming it's unacceptable.