You should add the Grand Prix Audio Monaco to the list. I have experience with all three and prefer the GPA. I have only tried the Kuzma with the GPA.
I have no experience with the SRA, but I have heard the HRS and the Grand Prix. The Grand Prix is a very fine product, but nothing that I have experienced comes close the the HRS. I have heard four different systems using the HRS MXR stands and HRS platforms. On two of the systems I listened to electronics on both the HRS and GPA. In my opinion, as well as everyone else that was there, the HRS is a stature way above everything else. After I heard it transform a friend's system from one that I hated into one that I liked, and after I experienced an AB session at another location, I jumped in and purchased many of the HRS products for myself. These products isolate your product as if they were in an incubator from the outside world as well as their own foundation and chassis. I have a double wide system in a burled walnut finish. On top I have a non-suspended (like the Kuzma)Brinkmann Balance table (which I am also very happy with the product, the company and the customer support). There are no other products that I am aware of that look as refined as the MXR stand and that give you the option of either a contemporary (painted finish) or a traditional (wood) appearance. My stand is built exceptionally well and it keeps my all tube analog (six chassis) system tamed. I also have my amps on their stands and my amps have 19 tubes each. This system does an amazing job with all of my melodic tubes. The build quality is exceptional and the customer support has always been there for me whenever I have had any questions. These guys know their product and probably know your components and what works with them as well. This company goes out of its way to make sure that everything exceeds your expectations. Their products are well engineered, well built, well packed and well delivered. You do pay the price, however, as their top of the line products cost several times that of everything else. In my opinion, it is money well spent.
You have tried the HRS M3 (with the correct feet for for product put on it)
with Spacers and Couplers in a MXR rack in your system??? I find that hard to believe unless you are a dealer for HRS.
I have all HRS under my Voyd TT after having a MS 4" platform with brass feet. I sold the MS the same day I installed the HRS.
HRS has been the most addictive product I have bought. Once you here what it does to you gear you have to have it.
Most who say I have tried both as you have talk out of their AS.
So please show me up and make me eat crow and tell the truth.
I have not tried the SRA but I am sure it is a very fine product.
I am not familiar with the Harmonic Resolution isolation racks and bases, but from reviewing their Website and reading the 6moons Review, it appears to be a fine product.
I have not heard the Grand Prix Monaco isolation rack either, but I did have extensive discussions with the guys at Grand Prix and did read everything I could find about their products. I also thoroughly investigated Finite Element.
In the end, after months of reading and talking with the various designer-manufacturers, I decided to go with Silent Running Audio and Kevin Tellekamp, and if I had it all to do again, I would make the same choice.
You can view my system at http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1170310300&read&3&4&
To understand a bit about Kevin's design, you can read the following reviews, especially the 2006 Soundstage review. And then I would recommend calling Kevin and talking with him before you make a final decision. The HRS MXR rack and the SRA Craz rack are in the same price range.
Hope this helps.