Somewhat hate to post this but just upgraded to a Quadraspire SVT. I've had all sort of devices, Sorbothane, Stillpoints, spikes, the list goes on. I have seen no difference at ALL from all of these things. I finally got a difference from the Quadraspire. A big difference. I do wonder if you need to get your system and rack to a really high end before you start tweaking. Thoughts appreciated.
I think that supports, cabling and mains affect certain aspects of hifi reproduction, so if your system doesn't have its strengths in those areas, you'll not experience many meaningful benefits. Cabling and mains appear, to me, to affect the amount of energy the system can create. But better cables will also help keep that energy coherent, ie all the right notes, in the right order (to paraphrase Eric Morecambe).
More energy out can then create problems if there is any sort of microphony, so a bigger feedback loop. That's where the supports come into their own.
So if your system isn't particularly good at getting musical energy off the medium and into the room, supports won't do overmuch to help. And if your system gets the energy out, but in a muddled or less coherent fashion, then supports won't fix it (though they may help somewhat).
There are high end products which don't do the 'energy thing' as well as lower end ones, and (shock, horror) there are high end products, including cables, that don't help the coherence thing overmuch.
In short, I don't think it's 'high-end' vs 'low-end' that matters, but rather, energy and coherence.