X2
I have my 6k tempur pedic collecting dust.
It was wonderful at first, but same issues. I would wake up sweating, and it developed dips. I only weigh 160lbs and my girlfriend weighs under 120lbs. Complete waste of money.
I have tuft and needles in all my rooms now. While I'm not blown away by the comfort, I do sleep much better.
They also offer a 100 day trial. No questions asked, if you don't like it they will refund you 100% and will send someone to pick it up, and they donate it.
$700 for a king too, which is dirt cheap.
https://www.tuftandneedle.com/mattress/?size=tn23t