We purchased a hybrid split king (two twins) with adjustable frame.  We have only had it for a couple of weeks but so far, has helped us sleep better.  It is incredibly comfortable.  OUr model has the head and foot massage/vibration also.  I think the only thing that could make it better would be to have a heat feature for those really cold nights.  

I was concerned about the center and worried that the twin mattresses would separate; and they very well may but they fit perfectly in our king bed frame and that is not an issue for us.  

I highly recommend this bed.