It seems like you and albert both moved away from isolating racks like the GPA (which I currently use for my amps and line stage) to a more rigid stand and then use separate aftermarket decoupling, like the wave kinetics?
Speaking for myself...this is what i have sought to do. 4" inch thick birch ply shelves (400lbs approximately) sitting over massive 1" thick slab of slate. The Nimbus couplers/dampers and the Artesania dampers (on audition) then are applied to the various components.