Treelore

my 2c worth. A scarf that is smaller in height will allow a tree to snap the hinge earlier resulting in a tree laying flatter. This is not controlling how a tree falls this is controlling how a tree lands The fact that you are not having two even surfaces come into contact but the top cut resting on a very small surface area begs for lack of control especially if the tree had an irregular shape. You would have pressures exerted on the outside uneven edge of the tree and possibly pushing of the tree out of direct fall. I fail to see how by cutting out a block you have achieved anything that you wouldn't achieve by cutting a notch of the same height as your block cut. You are also going to get different responses depending on the height of the vertical cut because of where the top horizontal cut will actually meet the lower wood to close out the hinge. All of these variables make for an extremely complicated scarf that I am not even convinced has a merit.
This post is not intended as being inflammatory I am just really wanting some hard and fast surety of a single "actual" benefit.