Carlos,

Sorry I was editing while you were posting.

I can see your point with scoring. But to me it seems a bit much.
Paring end grain with a chisel in my honest opinion is a %^&$% and seems to let ones sawing abilities not matter. They should in my opinion. Take half the line and be done with it.

As far as square rule vs. mill rule difference. As i see it you work from reference face to a set dimension on both, but in square rule you are probably left with more wood to cut out for housings to meet the "perfect" timber. That means that only structural housings in mill rule would be present but in square rule you have those housings for everything. Like braces. Braces don't need housings to brace do they? The bearing point of the tenon carries that right? Anyone?

Peace, mo