I have the HRS M1R rack and six M3 isolation bases. I started out with just the rack because someone locally was selling it and wanted to keep the M3 bases. I made my own shelves out of MDF, 50 duormeter Sorbothane, and granite to get me by until I could cough up the green for the HRS isolation platforms.
I agree with Gwalt that HRS provides speed, focus, black background, and natural decay. I obtained that result with the rack alone. When I added the M3 bases, those factors increased. I'd say I got 40% of the benefit from the rack and 60% from the M3's. I am on a suspended wood floor, so if you're on concrete the percentage may be slightly higher for the bases.
I later purchased a pair for my monoblocks which do sit on the floor, not the rack. There the improvement in resolution and detail was also very noticeable.
The Rockport Sirius turntable sits on a stand that was adapted from one used for electron microscopes. With that exception, I don't think there is a better foundation for a turntable on the planet than the HRS M3 base. You'll think you just upgraded your cartridge by 50%.
If you read up on Mike Latvis, you will find that he is a materials science engineer. The M3 bases are an aluminum alloy, but sandwiched inside are 6 or eight different metals which are designed to absorb different vibrational frequencies. The rubber compound which suspends the M3 footer is derived from his experience designing vibration control for helicopter rotors.
The HRS Nimbus footers, couplers, and damping plates can also be very effective. But I have found that all such devices (Stillpoints, Symposium, Aurios, HRS, etc.) are very component dependent. It might make an improvement, it might not. One is not better than the other except in a particular application.
In short, if you have the money and space, don't hesitate to invest in the HRS rack and isolation bases. They will make a significant improvement in your enjoyment of music.
BTW: I assume you have already invested in one or two dedicated circuits, audio grade outlets (I use Isoclean; Oyaide is also excellent), and power cords of the level of Shunyata Python or better. A solid power delivery foundation comes first, then you can realize the benefits of a solid structural foundation.
Have fun!
