I'm a 1,000 yard benchrest shooter. I did try RWS primers in a couple of my rifles; they shot worse.
Now before you think "Oh, I read somewhere they shot worse," the point of this post is that I took a load I had worked up that shot well with Fed 210s, and simply changed to a RWS primer. No conclusions should be drawn. It is sad but true that different rifles, different barrels, different powders will sometimes show a preference for a certain primer. You can't conclude from that that a certain primer is "better."
I have one rifle long-range rifle that shows a distinct preference for the old 9-1/2 Kleenbore primers. All the modern ones shoot about the same, but the Kleenbore just tightens things up. Go figure.