You may be misunderstanding the product--it's a topper that goes on top of your existing mattress. It doesn't replace the mattress. I do indeed have it on top of an old school analog expensive mattress. It cools/warms to the desired temperature without impacting the comfort from the mattress. I don't think there's much room for snake oil here: it pumps cooled or heated water through the mattress topper. There's no mystery.

> But is it more comfortable, then say, an old school analog expensive mattress?

Mattresses wear out, and people end up keeping them too long. Somewhere like walmart.com sells great mattresses for inexpensive prices. They are not related at all to what they sell in stores. Because they are inexpensive, as soon as they start to wear out, buy a new one.