No need for FUD. Loss of Yaw Damper is not something that would endanger an aircraft
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)
My interest was more to the weapons system testing itself.
These jets cannot fly without GPS.
When they (the military) knocked out GPS intentionally around China Lake NAS a few months back (for testing aircraft in GPS denied environments) -- all Embraers were told to avoid the area:
THIS NOTAM APPLIES TO ALL AIRCRAFT RELYING ON GPS. ADDITIONALLY, DUE TO GPS INTERFERENCE IMPACTS POTENTIALLY AFFECTING EMBRAER PHENOM 300 AIRCRAFT FLIGHT STABILITY CONTROLS, FAA RECOMMENDS EMB PHENOM PILOTS AVOID THE ABOVE TESTING AREA AND CLOSELY MONITOR FLIGHT CONTROL SYSTEMS DUE TO POTENTIAL LOSS OF GPS SIGNAL.
https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_...