It's debatable whether or not it reduces RADAR range, but I can assure you that you've completely eliminimated the V1's ability to pick up LIDAR scatter. I really think that for the extra range the 6" may or may not give you that you're better off bringing it down below the RVM. Also, you've reduced your ability to pick up laser from the rear.
I do know guys that have mounted in that area take a razer blade scrapper and remove the dots. To me that's a little extreme just to mount the RD 6 inches higher.
I go to www.radardetector.net and it's a great forum. If you search it you'll find all kinds of posts on this very topic.