Ours is a what they call a Tempur-Pedic Split King (Allura model) I went ahead and bought all the bells and whistles, complete with motorized and vibrator settings.
Our Split King is actually two twins matched together, and this has come in very handy, especially after my back surgery. Yes it cost lots of money, but for us, it was worth it.
One other thing I wanted to mention, is that if you have a back problem,.....there is a good chance that you may be able to write it off as a medical expense. My surgeon wrote a script
type recommendation for it, and we were able to write it off.
There are lots of good beds out there, so I'm not going to knock any of them...it will always be a personal preference, decided by comfort and cost.