I read with interest the Casper vs Endy article and I am not surprised by the conclusion that the firmer mattress was cooler. That will always be the case with a firmer model because the less you sink into a mattress the less your body is surrounded by foam and therefore the better it can breathe. As to who the winner was that's always in the feel of the beholder. I am sure they are both good products.
Nine Clouds has similar all foam matress models on display in our west Mississauga showroom at prices that are lower than these two brands for a similar quality and the best thing of all is that you get to try it before you make a purchase. The online brands offer 100 night sleep guarantees because they have to or they would be flooded with bad reviews. Industry numbers I have heard suggest that about 20% of these mattresses-in-a-box get returned which is not surprising because given that they can't be tried first.