I don't rate hi vis jackets at all, at least not in an airport environment. The brain processes mainly shape rather than colour, and the torso / shoulders is one of the primary cues we use for spotting one another.
Now, if you are lost at sea or standing by a road at night then obviously it'll help, as the viewer sees a bright object against a dark background. But your typical airport pan is bathed in bright orange light, and covered in things that are either white or already painted dayglo.
All a dayglow jacket does is break up the distinctive "human" shape and just provides the viewer with one more bright object to be lost among all the others in their field of view.
So, whether a hi vis jacket *actually* helps you be more visible is highly situational.