I have both the Radius and Rack of Silence, and all the "accessories".
With Radius, you can add additional springs under each shelf to further isolate the shelf from floor vibration.
With the Rack of Silence, the "shelves" lock into the posts. The reference level rack of silence give you the choice to convert the middle two sections into spring supported shelves. You get two sets of springs with different load limit. These springs are heavy-duty types, so you don't have to worry about them getting loose over time.
With heavy equipment, you don't use the springs.
I have my Pass X350.5 (140 lbs) sitting on top of 4 discs of silence on top of a rack of silence amp stand and it works just fine.
The shelf is made of cross wood beams, so I don't know how the static would be transferred. As for heat, the cross wood beams allow good ventilation. I added one additional shelf to my rack so I have 5 shelves holding my components. They are extremely close to each other, and I don't have any heat issue.
FrankC