Magnetic isolation

Geoff, my statements don´t conflict (maybe a little typo though ?).
Try this: A heavy deck needs strong magnets but not TOO strong. Then gap between deck and feet becomes too long resulting weaker magnetic field and thus more unstable balance. The essence is dense magnetic field between deck and feet, as dense as possible in fact.
2 mm gap gives denser magnetic field. 

The more dense magnetic field results to stronger magnetic force and thus better stability. The magnetic push needs to be just enough. That´s the trick :)

Indeed, a dense magnetic field utilizing magnets that are suitable for the load.
I think the gap I have is about 2 - 3mm. 

That´s good... maybe you could try about 1 mm... ;)

Ha! I'll employ some mass & see if there is any difference...

It’s not that a wider gap translates to a weaker magnetic field. For a given load a wider gap actually translates to a stronger magnetic field. So if your gap is say 1 mm now, more powerful magnets would produce a 2 mm gap or whatever for the same load. As long as there’s a gap there is levitation. It’s the levitation that’s the issue not the flux density of the mag field per se. Hel-looo!

interesting article on mag lev for audiophile applications, see link below:

http://www.gcaudio.com/products/reviews/infomagix.html