Well, Grsecurity did maintain their own Linux fork for the past ten years with an excellent security track record. The issue is that mainline is not interested

Well, Grsecurity did maintain their own Linux fork for the past ten years with an excellent security track record. The issue is that mainline is not interested in merging it, leaving most users vulnerable (since using a Linux fork in a production environment is something most users aren't going to do, even if there are clear benefits).