Done my own thing, and have a RSW12.
I got a floor tile in my carpeted living room and tried with and without the tile, and the tile sounded a lot better.
So I took the spikes off, because with the spikes it did not seem that stable, with the rubber feet, its very secure, does not move.
I never noticed a sound difference, but its probably better with rubber becuase of the vibration, better to have rubber and be solid, but with steel you will probably get a bit of resonance, I dont know, I am just trying to sound smart.
But I have rubber and prefer it.