I've never used any Royal Purple products. I am however a fan of the PowerBlock television shows on Spike TV (and similar shows on other networks). I believe Royal Purple is a sponsor and I've watched multiple episodes where they change all of the standard fluids and replace them with Royal Purple synthetics. I realize they are testing on a chassis dyno and replacing more than just the engine oil. They usually change rear gear oil, transmission oil as well as engine oil. It is impressive to see gains with the fluid changes, no matter how small. I have no idea how the Royal Purple would compare to other synthetics. I've only seen them compare it to conventional oils. You can watch some video clips on this site.
http://www.royalpurple.com/video/video.html
ddb