This is true. So you have a choice between a single chamber bed or a dual chamber bad. With a dual chamber bed, each person can choose his/her own Select Comfort settings - but there's the annoying thing in the middle. With single chamber, there's only one setting, but no annoying divider in the middle. I actually exchanged my dual chamber mattress for a single chamber one because of this.
The annoying thing in the middle I perceived as a trough. If I moved toward the center I was sinking. The help desk sent me some additional foam to stuff in there so it's hardly noticeable. The lumbar effect from the Select Comfort is far superior to another air bed we have used.