I attended a seminar on a product called HeatGuard. I've since found similar products - RadiantGuard and Prodex. All these products can be installed on the attic floor over top of existing insulating material. The HeatGuard people gave me a quote of $ about $3600 for a 1730 sq. ft. attic. I'm concerned about effects of the high humidity in Raleigh, NC, and the seemingly high cost vs savings that might be less than 20% on the average. Anybody have any experience with any of these technologies?