Anybody still using soft rubber isolation devices?

Yes, but not for my stereo. :)

I use Herbies Iso-cups in conjuntion with Gabon Ebony balls under my transport and preamp.
My Hydra and Dac rest on thick Maple blocks with different composite footers.
A lot depends on what component, weight, type of shelf and or material they're on.
Experimenting and proper compliance (soft, medium, hard) is the key factor in determining my sound.

it is my experience that hard objects "enhance" resolution, while soft objects "attenuate" energy in the upper mid/lower treble region. yes, this is a generalization and i can mention a few exceptions, such as dh cones and dh squares.

i prefer soft objects such as sound fusion sound boosters, furniture foam and memory foam.

i also have foam cable lifters manufactured by westlake audio.

ball bearings on dollhouse ceramic plates might be worth a try

they are cheap & easy to test if you have an understanding wife

Many years ago I bought into the hype around Black Diamond Racing cones/pucks.  I invested quite a i bit in their products which now sit abandoned on a shelf in my listening room closet.  With as musical as my system should have sounded, there was a hardness to the upper midrange and lower treble using the BDR products.  That's objectionable on its face but worse yet, it made for a disjointed sound and soundspace.  (I'm not intending to bash BDR products as I don't doubt they can be effective in specific systems)

Then...I discovered Herbie's Audio Lab and their Tenderfeet.  With both regular hardness tenderfeet and extra firm versions for very heavy components, I realized a linear upper midrange/lower treble response and a coherent soundspace.  To this day all of my components are damped with tenderfeet.

I also use Herbie's decoupling gliders and bases to decouple my speakers and subwoofers from the room.  Smoother sound and tight deep bass that is not transmitted through the rest of the house as before.

The rest of the family really likes those devices!