I have not see this product before this post.
http://www.auralexelite.com/sound_isolation_subdude/sound_isolation_subdude.asp
The website offers little information. It appears to be a sheet of plastic granite "Corian" with light weight or acoustic foam under it.
Having not heard or tested this product, I'd suspect it would lessen the energy being transmitted a sprug floor (wood floor) which just may be your neighbours ceiling.
Is this always a good thing?
For my own system I prefer a sand-box type system (like those offered by Brightstar). The sand absorbs the excess energy so the energy is not transmitted back up into the subwoofer enclosure.
To answer your question, measure the three spike locations under your subwoofer. These points are the ones which require proper support and footing. If you are not using the provided spikes or four rubber feet in some cases you may have created a problem that needs fixing first.