Loss of attitude info is a serious business, in the worst case the pilot may be left to fly only "raw data" and using the backup "steam gauge" instruments, because the displays and automation will stop working. Such event is no cake on a big jet, even during daylight, perfect weather and with the crew perfectly current and capable to fly like that.
Murphy will have it that it happens during night, in a storm and most crews today are trained to rely on the automation and rarely getting to hand fly, even less raw data, without any of the computers. The result will be another AF443 ...
And it's AF447
That doesn't mean the plane can't fly. But it does mean that the pilot is going to have to fly it differently to avoid dutch roll, possibly flying at a lower altitude.
Keep in mind that this is aviation, which is very risk averse (by necessity). Even minor issues are treated as significant.
(the fact that it's a smaller aircraft might imply in having some certification differences as well)
