I did a setup similar to Gert"s on a 6.2 (I7 Quad), same SSD 512GB M4, but I added Crucial's 16GB ram. It absolutely flies.
For Francesco De Giorgio, you need to boot off the Mountain Loin that shipped, don't ask me why, but normal OS X downloads aren't working for these upgrades (you see it all over the inter web right now), something is unique, the what shipped, which leaves cloning the original drive as the best option at the moment.