Grand Prix Formula vs BDR shelf for source

under a turntable do they differ sonically? I want a good shelf atop my rack for my TNT to call home. both are available in sizes large enough, and both are obscenely expensive, although the gp is $600 less retail. any others I should consider besides symposium?
I have one on my LeMans stand under my Nottingham turntable. What it does is liven up the sound a little. I've never compared to anything other than the stock acrylic shelves. I suppose they do sound a little better than acrylic but they sure are expensive.
Get an appropriately sized Gingko Cloud. I have one sitting on my Monaco under my Scout. It's very reasonably priced.
I find Stillpoint feet with Risers very effective, but obviously it depends on the deck and rack. They are much cheaper
I use a BDR base under My Basis 2001 turntable and like it much better than the MDF board the Solid Steel rack came with. I also use BDR cones under the BDR base on top of the Solid Steel rack ,I did not like the metal cones the Solid Steel rack came with I think the MDF sounded a little dead under the turntable with either metal or the BDR cones but the addition of the BDR base is nice . Bottom line I like the BDR base and BDR cones under a turntable . Marc
I have a BDR "The Shelf" under a Project 9.1 with Benz SM the sound is lively with quiet backgrounds and good dynamics. I use Simms Novcom Pucks under the Shelf for isolation, you could use Sorbagel or BDR Cones but I think Sorbagel(used on GP Audio racks) would provide better isolation and not make the music lifeless in combination with "The Shelf". The price is a little more than half "The Shelf for Source" price.