It sure does give you extra slam. You can have less subwoofer output and still great experience with bass intensive moments since you feel them.
That is why i started using it. I bought them 2nd hand from someone with a wooden floor who had mounted it wrong. It did not work very well there.
With my riser (no idea if this is the correct word) it works very well.

I read you are from Danmark, perhaps you can visit a german dealer:
http://www.bts-privatkino.de/

I have ordered the rubber isolating feet (Kinetics shock absorber) via him, a nice person to deal with.

Sold all M equipment