This is a bit older thread, but I thought I'd report some successful findings.
A few months ago I aquired a pair of Soliloquy 5.3i floorstanders. Great speakers! I'd been trying several types of footers to get the best balance, musicality, clarity, and bass.
With my older Soliloquy monitors it was no contest. Vibrapods hands down for clarity and great tone, exceptional liveliness, and even a little bass boost and growl.
With the floorstanders I tried several variations of vibrapods, different configurations and ratings (#4's and #5's). I got the clarity, tone and musicality I wanted, but the bass was always just a step behind the music and a little sloppy.
Another product I'd tried with the monitors are a cork and rubber product called Isol-Pads available here on Audiogon. They did a good job of decoupling the monitors but lightened the bass unacceptably. On the floorstanders however they have been great! Clarity is still good, the sound is very clean and musical and now the PRAT is back. Bass is appropriately quick and even, and still with satisfying weight. Low level liveliness is good, much better than on spikes, but not quite up to the more energy preserving vibrapods.
I would encourage anyone who wants to try decoupling their floorstanders to try the Isol-pad product. They are not at all expensive.
Chris