Attended monthly stamp club this morning with SU group. Tried the demo's diagonal plate with my Martha Steward Score Board -- and it fit just perfect. Because it is "open" at the bottom and at the right side, it works great. And the little "feet" parts on the underside of the diagonal plate stays in place nicely...no movement or slipping when scoring. Made me happy since I will be getting the diagonal plate without having to buy a new scoring board.
Oh! And I do not use the bone folder/scoring tool that came with the board. I use the double ended stylus I had gotten from SU when they still sold brass embossing templates. I use the larger ball end on thinner DSP and the smaller ball end on cardstock and the Designer specialty paper that is thicker like cardstock.