I carried out some trials and thought I'd report on my findings.
There are benefits, exactly as described by the Symposium website:
http://www.symposiumusa.com/faq.shtml#1I bought Symposium Svelte Platforms, two 19" x 24". The cost was $1,300 - not cheap. It may be possible to use smaller (therefore cheaper) platforms but they will be smaller then the feet of the RM30Ms. They are 5/8" high so have minimal impact on raising the speakers. My speakers sit on carpet which in turn is on a rubber/foam sonic insulation of about 1" in order to reduce sound travel to my neighbour below. This apparently is not ideal as it's better to use these platforms on a hard surface. Following advice, in order to level the speakers I used slivers of metal underneath the platforms. Of course I had to try and get my speakers exactly positioned as they were before - distance from the two walls, toe-in, and distance from my ears. This took around two hours! So the speakers sit on the platforms which sit on the carpet - no cones or other footers are used.
In my listening tests I was trying to hear if I could detect more percussion details on specific tracks. I thought I could but it wasn't really significant. After getting fed up with this I thought I'd try and relax and just listen to some of my favorite music. I wasn't too disapointed because I had already tested the platforms under my gear with good results I thought.
At first the music seemed louder then normal yet I was listening at the normal volume (I can set the volume exactly and note the volume levels for each CD). Then I realised that all instruments and voices seemed more seperate and more defined. In particular things like piano and rythym guitar which were usually in the background seemed easier to follow and very enjoyable. A violin came in with a sharpness that was unexpected. Kick drums on some tracks could be felt when they weren't before. These are I understand all symptoms of lowering the noise floor, which is exactly what Symposium claim they do.
Since then I've been going through my favorite CDs and I hear all this with all of them. Nice!
I think there are only two other ways to get this sort of improvement - better power supplies, and better extraction of data from the CDs, by cleaning say.
I would highly recommend trying these platforms under the speakers (and under your gear for that matter -I've got a sophisticated rack yet improvements, particularly under the CD Transport and amp can be had).