Don't wish to question DC as he's a pro and has been at it for a long time, but does it work well using the bench top to run the plane on?? Every design I have seen and used has had a baseboard you can keep polished or waxed.
I just completed a shooting board based on DC's design. I placed it on one-half inch MDF to protect my bench. I extended the half inch MDF about 2.75 in. on the left and right hand sides to accommodate my plane. I also extended it about 5 in. beyond the fence for a longer runway.
I followed the plan Alf linked to in her post. At the bottom of the first page, DC mentions that thin MDF can be used to protect the bench, although he doesn't do this in the DVD. After all, it was probably LN's bench anyway.