I had occasion to sleep on one of these foam-type mattresses some months ago. It was quite comfortable in the way that it accommodated to my body contours but at the same time (and this was in the summer) it seemed to retain much of my body heat in a way that a traditionally sprung mattress does not. It felt like sleeping on top of an electric blanket which was "switched on" all the time (and I'm usually quite a chilly mortal.) If you think such heat rentention might be a problem for you, try and persuade the supplier to let you have one on approval first.