wracks71 (I think that's his name) is running all RMS stuff in his autox (or road course) car. Don't know of anyone running an HDK professionally. I'm definitely interested in seeing how you like this suspension, maybe I'll have to get one some day!
Yeah, I'll type up a good write up on the install, my thoughts and such this week/weekend and get it posted with more/new photos. Really, in summary, I couldn't be happier with it at this point, granted my drivetrain isn't completed let alone installed yet so I dont have personal hands on driving time with one yet.