Suspensions on turntable...really effective?

Go to the Minus K website for some real good info on isolation. You can get one of their platforms for around $2500.

Only ones I ever heard that really made a difference were magnetic suspension , And I 've owned  four Thorens and a Linn LP-12 .

Sounds of Silence Nashua NH The Vibraplane, which is a lab grade microscope stand but no where near 10K.  

Many years ago, I had a Linn LP which was so critical I could tell how many people were in the room by what the turntable sounded like.  I have a Superscoutmaster Rim Drive now located on the lowest floor of the house with no basement....bedrock.  Sounds terrific.

I'm not quite sure that I fully understand your question, but I will say that a good suspension will definitely isolate a turntable from footfalls and other vibrations.  A stunt I use to prove it to non-believers is to hit the suspension of my Basis Ovation turntable with a hammer (covered with cloth to keep from marring the suspension, of course) while a record is playing.  None of the energy from the hammer is transmitted through the speakers.  While my prior (non-suspended) turntable, a Well-Tempered, was pretty good at isolation due to its mass, it still could be affected by vibrations from heavy footfalls--it clearly could have benefited from a device like a Vibraplane or Seismic Sink, but they cost more than the table and arm itself.