One thing you guys need to keep in mind with these devices is the type of floor that you have.
If you have a wood floor, suspended floor, and any type of floor that can move, then these devices can really help keep the speakers from mechanically moving or flexing the floor. And the benefit can range from minor to significant as the flexing or moving floor in turn moves the speakers, electronics, turn tables, etc.
And they aren't technically isolating the speakers from the floor. The speakers are still coupled to the floor. What they are doing is applying a damper. It is just like the car that you drive. The shock absorbers damp the ride and give you a smooth ride. But the car is not de-coupled from the road. The car is still coupled to the road via the wheels and tires. Likewise these stands are still coupled to the floor but there is an added damper or shock absorbers.
However, if you have a solid concrete floor then your best option is to spike the speakers straight through the carpet and onto the floor so that they do not move.