We have had a king for over 15 years. I think it's their upper middle offering. It has been a very good bed for us. We had to replace the mattress cover as it separated on the side (they replaced it after a minimal cost 7 years later- I think it was at 75% warranty) and gave us a better mattress (has memory foam topper). We also upgraded the air pump for $100 as it quit working (might have been an electoral surge). The original did feel hot in the summers, but the memory foam topper (it's 7 years old) has made a major difference. My sleep number is about 20 clicks different than my wife's setting which does make a difference, but it does not feel like it is two different beds.
The other major advantage is it breaks down and is easy to move (we have moved 4 times with it) and if you have narrow steps, you don't have to cut the box springs (although, I don't think that's an issue with memory foam beds, but a king size memory foam has to weigh a lot and hard to to handle after its used.
The newer ones with all of the sleep technology I can't comment on. As long as you get a pillow top or memory foam, it's the best of both worlds.