coming up on 12 years for mine. I would spent the money again in a heart beat.
However, after 12 years, It is not nearly as firm as it used to be.
I weigh 350, so that might have something to do with it.
I am a back and side sleeper, depending on how my back feels.
The newer ones have choices. Mine is the old version, and there were no options.
In the newer beds, I think I prefer the firmer model.
They do feel warmer than other beds to me. I am ok with that. But also, my old bed sleeps "softer" in the heat than it does in cold weather. We open our window even in the winter, and it makes a big difference in the firmness level.
The first night I slept on it, it felt like my back was in "traction". Almost like some one was pulling on my legs to stretch my spine.
The second night I was out, and really slept like a rock!
It got to the point where I was so glad to lay down and feel my back relax, and stretch out!
It does feel different moving around on one, compared to a regular mattress.
It does not transfer motion, which is a huge deal. You can roll around and not wake your partner up!