For material hold down method, I use screws, straight the material and into and through the spoil board.
I used to have two layers, bottom layer of OSB, and top layer (spoil board) of MDF. The screws would go into the OSB and bite and hold really good.
I currently have two layers of MDF, and it does not hold screws as well, easier to strip out. I kinda wish I had put a first layer of OSB, and then MDF on top.