I had a tempurpedic CA king. It was great. I honestly could not feel my 120 pound Chocolate Lab jumping on the bed, or my 300 pound ex getting in or out. Never had a problem with it. No sweating on my side, but the ex did complain of that. (she's one of those who gets up to funk with the thermostat/fan 10 times a night)
I have a lower end Sealy in the Puma (RV King size) and its not bad, but you can hear the springs.
If you wouldn't do that at night, the springs wouldn't move
I tried one of the tempur beds....liked it a lot; it had the new anti sweat layer thingy on top. 3K. Gonna look at a sleep number bed this weekend.