So here we are --
Now that I look at these, I'm a bit embarrassed. And that picture doesn't do the horror of the old bed justice. Yuck. They say that more than an inch and a half of sinking in the middle is a "defect". Well, as close as I can measure, my old bed had sunk at least three inches, and that doesn't count how high it probably was when it was new; that's just how much lower the center is than the edges.
I think I'm going to go take a nap.