Why is there little interest in RTS couplers?

It's probably because us'll don't believe that RTS is the best way to go. Sometimes systems sound worse instead of better if components are tightly clamped. Plus it's ugly and could potentially mar a component's finish.

In my personal experience I've had great luck using different types of footers to achieve the sonic differences I'm looking for... and the particular footers I use are not real expensive. They actually don't need to be expensive to work well and what footer works well for one component might not be the best choice for the next one.

I'm glad you like your rack but as you know, as with most things, it's different strokes for different folks and there is almost always more than one way to achieve a disired result.

Have you actually heard a system prior to its use, and then at least 10 days after it's in the system to compare the sound?

The problem in my eyes is the inability for the company to do a QUICK before and after on the spot demo because of the need for settling in for many days to get the sound benefits. One would have to know someone's system quite well and have a revisit later to be dead sure of the positive changes.

It marred my system. Big old scratch on my past Cary CD p.ayer. Yikes!

I have Sistrum racks for all my equipment. They make an instant improvement in all areas of sound--clarity, beauty, dynamics, bass, blacker backgrounds. The sound improves for several days. Before, I could only guess about the RTS couplers (Audio Horizons is now the makers of these). Now I know. I was able to purchase 3 sets of couplers from a prior user. He still uses couplers under all equipment, but no longer need these as he simplified his system. For those not familiar with Sistrum racks, they are designed to drains unwanted vibrations to the floor quickly and thereby allow more information to be heard. The RTS couplers have a similar purpose.
The only drawback I had with the Sistrum rack is that the equipment is perched on 3 sharp points so that your could tip the component by accidentally leaning on the back corner or you push a button too hard and physically move the component on the points and scratch the bottom. The RTS couplers solve this problem 2 ways: 1.) They have 2" solid metal pucks that replace the 3 points on each platform. The 2 pucks are located towards the front and rear of each component and towards the midpoint L-R. The top coupler is a 1 1/8" W X 3/8" H and is 2" longer in length than your component is wide. It is a solid bar with a hole on each side of the bar about 1/4" wider than the component. The bottom coupler has a threaded hole so a 1/4" threaded rod can be screwed tightly into it. The underside of the bottom coupler is solid all the way across so the rod can't go through it. The top coupler has a thin film on the bottom of the bar so it will not mar the component's finish. The couplers have very heavy wingnuts or larger turning knobs that are threaded which are screwed on to the rods from the top of the top coupler. The bottom coupler goes under the shelf. The bottom and top holes need to be lined up once the rods are screwed into the bottom coupler. You just tighten the wingnuts and make sure the component stays level--use a torpedo level. Tighten by hand firmly. Each coupler takes about 8-10 minutes to fasten. No component will ever move.
How is the sound? Prior to installing these, the Sistrums racks were the single greatest sound improvement I've made in my system. Here's the weird kicker; the couplers take about 7-13 days until you hear the improvements and will continue to improve for a couple months. Initially they may sound slightly worse. Once those 13 days are over, however, the difference in sound is just amazing--just like the Sistrum racks, but more so. I feel blessed to have gotten 3 used ones, but even new, what a deal. Even if I were to have paid about $600 for the 3 total from AH, I can't think of another way to improve the sound of your system that much for such a price.
As for the looks, everybody who's heard my system doesn't even know they aren't part of the Sistrum rack. The couplers were made by a now defunct outfit that made the incredible RTS rack (to hold 3 components) that sold for $12,000. Mine now has most of the technology of the original rack for much less and I'm holding 5 components.
If none of you ever buy these, no hair off my head. But if you do, give them the 2 weeks and be prepared to fall seriously in love with your music all over.
If you want more info, contact AH.