The hinged rear cutter also gets out of the way when cutting. At some angles, the depth of cut may be limited since a fixed rear cutter would sit down on top of the back of the cut.

I use my fixed cutter scraper for compacting gravel by tilting it down as far down as it will go. It rides on the back of the rear cutter when I drive forward. I don't think a hinged rear cutter would work for me.