I spent about 90 minutes doing a lie-down comparison of latex & Tempurpedic mattresses this week.
"The Latex mattresses to me felt squishy. The foam mattresses feel more like sand, if that makes any sense." That's a good way to put it!
Mattresses are very much a matter of personal preference. Unfortunately for me I seem to prefer the most expensive Tempurpedic, the Allure model. It's 50% denser that the regular model. With the pillow-top 3" layer it's amazing - without it, it's kind of a brick. Sigh - gonna have to sell off a lot of knives to pay for that!!! But putting in the time to test them all was really worth it. What I thought was fine at first turned out to be fine, but not GREAT, like the Allure is - but I had to go back and forth between many mattresses at 5-minute intervals to be sure of the relative merits and deficiencies of each.
The Deluxe model and above do have a better air-flow system than the cheaper models. As for the knock-offs, I have examined those too and the foams vary a lot (Bed Bath & Beyond has a 2" topper that I found to be much superior to the 3" topper from another maker). But none I have seen are as dense as the Tempurs. Supposedly the Tempurs with air-flow system are much cooler than the originals or the knock-offs. They felt cooler to me when I was testing them out. Cooler even than the latex beds I tried.
The salesman told me that it's best to lie a Tempur mattress on the floor and walk on it regularly for the first couple of days, to break it in and speed up the off-gassing process. They are kind of plasticky-stinky when new.
I slept on the floor for 6 months at one point, and it's not that bad, BUT as a side-sleeper I ended up tossing around from one side to another quite a bit. Also it doesn't impress the ladies when you invite them to your floor. I went to a super-firm futon, with a memory-foam knockoff topper, and that was great at first but in only 4 years it has gotten pretty uneven. So now I can't sleep through a full 7 hours - and I need 8 hours, so that's not a good thing.
The interesting thing I hear from people with Tempurs (who weren't freaked out by the slightly encased feeling) is that they will fall asleep in one position and wake up in the same position - no need to toss around to maintain blood flow, due to the uniform rather than varying level of pressure/support at all points of contact.
