"When the Phenom loses both GPS 1 and GPS 2 it also gives you an AHRS FAULT 1 and AHRS FAULT 2. For whatever reason this situation can cause the autopilot and yaw damper to disengage apparently, thus at high altitudes may cause the aircraft to dutch roll. I have had this exact situation 3-4 times, generally near the white sands missile range though and my autopilot worked great the whole time."
AHRS = Attitude and Heading Reference System
So basically, it seems it's not a big issue, especially since his aircraft kept the autopilot on. But it might require some attention from the manufacturer
If I was on an aircraft doing a Dutch Roll [0], I'd definitely feel discomfort!
(Note for readers: A "dutch roll" is when the plane rolls (when one wing dips down and the other rises up) and yaws (when the rear of the aircraft moves in one horizontal direction and the front of the aircraft moves in the opposite horizontal direction) at the same time.)
AHRS = Attitude and Heading Reference System
So basically, it seems it's not a big issue, especially since his aircraft kept the autopilot on. But it might require some attention from the manufacturer
Dutch roll may cause passenger discomfort though