Hi Gman52,
The Purple mattress is covered in the Simplified Choice thread here, and it has been discussed quite a bit on the forum.
You may click on the link for Purple here for other posts mentioning this product.
Purple uses a unique bucking column gel they call Hyper-Elastic Polymer. There is more about buckling column gel in this article and in post #2 here and the posts it links to and a forum search on " buckling column gel" will also bring up more comments and feedback about it as well.
Phoenix