Oxborne,
While I don't have the 30, I do have the 20/2. There is a way to approximate the performance of the 30 with the 20, which is by using the the clearaudio outer stabilizer ring.
This adds those characteristics which most people seem to attribute to the 30 versus the 20 -- blacker background, tighter, deeper bass, more solid images, and a greater sense of ease. It's a bitch to center since it's not cut for the SME 20 platter, but I wouldn't listen to my 20 without the outer ring.
I have, by the way, heard the 30 on many occasions, and agree that it's one of the last tables you'll ever purchase.
Cheers,
TRH