I went out and examined my seats to see if I could identify what people were considering uncomfortable or sub-par. It appears that the seats are formed as a plastic shell that curves around to the front and cups the foam portion. This hard plastic cup reaches around to about half the thickness of the foam and keeps that in place.
When I sit in the Z force my lumbar area barely contacts the seat back, and I cannot pelvic tilt enough to make my back touch the hard backing shell.
I just came back from an Idaho trip of a couple of 10 hour days in the seat and there was no discomfort at all, though I heard some complaints from my ATV mounted companions. (Based on a test ride I allowed to one of my ATV riding friends, he states he's about to buy a SXS.)
I have to suppose that with the limited adjustability of the CF Moto seats, they either favour one's anatomy or they don't.