Sandman,
You did some testing of the LI Celsion topper (folded 1" in half to make it 2" thick). What did you think of the material (overall and pricewise)
My main objective for the Celsion was to try to sleep a bit cooler. It did not seem cooler to me after a couple of hours of laying on it. I went so far as to measure temperatures of the Celsion, the flobed convoluted blended latex layer, and overstock mem-cool memory foam. I did not find (or feel) any signficant difference between them. So, I could not really justify the higher price, but it was not that much higher (15%?).
I found the 15 a bit too soft, so if I were to buy today I would probably get the 21.