I don't want the mantle of expertise on this issue. I just want to report excellent results with the light and rigid approach, when using Neuance shelving.
Mwalsdor, your rack arrangement goes in the opposite direction, plumping for mass in most cases. I am sure that there are lots of ways to skin the cat, but my experiments with the mass approach were not successful for me. The sound was often lovely, but the music failed to grab me. This is an odd thing. We can make our systems cause saxophones to sound beautiful, a voice to sound resplendent, a drum to be crashingly impactful and strings to soar. But this is not the same approach as seeking to remove all time smearing and go the PRAT route.
There are some that insist that their massy structures achieve PRAT. I am sceptical, I can't help myself. It defies my understanding of the issues, and does not gel with my experience. But I admit that does not mean I am certain that they are wrong.
The PRAT approach can result, in lesser systems, in a fast, infectious, but colored and fatiguing sound. The mass approach can result, in lesser systems, in a sluggish system where the instruments don't seem to be quite playing together, but often with good neutrality and powerful bass. At the pinnacle of each approach it may be that the sound quality converges to the same point.
But for me, I have found some form of previously unobtained musical bliss from the light/rigid/damped method. It is easy to implement, gets you great PRAT and is very neutral.
Get a welded steel rack that is spiked to the floor and supports its shelves on spikes. Get Neuance shelves. Possibly, use E-A-R feet between shelf and component. Simple and works great - you just have to wait a week while the sound stabilises - something to do with how the Neuance settles under the weight being applied to it. No need for cones, Vibrapods etc.
Almost everything in your shelf strategy Mwalsdor follows the opposing path with mass, and then has cones as a light/rigid interface to dissipate energy. It may sound great, and I have no reason to doubt that. But I reckon you would be surprised if you heard my system on my rack and would expect it to have a fresh vibrancy and speed that would make it very different from yours. What you may also notice is that your system had more bass weight and more solidity. I don't know which you would prefer, but I urge you to give the light/rigid/damped method a try. But throwing a Neuance shelf into your current rack is not the same thing.
I have to admit I am struggling because I don't really know what your rack sounds like or what you will like. All I can say is I am delighted with my rack, and it works best if I just keep it simple, no lead or sand filling, no concrete or granite blocks, no cones....