I've used both & prefer the look of fiber - there is a different appearance with the image on RC floating on the surface while same image seems to have a 3 dimensional quality on fiber.
Also, as mentioned above & in Ctein's Post Exposure the jury is still out on the longevity/permanence of RC. Many on the Pure-Silver list as well as manufacturers would argue that Ctein's observations were for single batch with one manufacturer; but there seems enough anecdotal evidence that the problem is pervasive. After reading what manufacturers have to go thru in order to try to make RC permanent, makes me wonder about the long-term reliability of the solution(s).