I've done some side of the stream, blade of grass in the teeth ciphering and figured a possible gotcha for my shed roof dilemma.
In the HSE report and the rigging research results thread and my testing it came to light that a spar log achieves a rotational velocity which is built up during the time the log lever pivots about the intact hinge or broken hinge with still being in contact. After it departs and loses contact it rotates at a constant rate till it either hits the Ddirt

)) or tensions the -ve rig line. A top rotates slower due to wind/air drag on the branches.
So it's possible that because of the existence of the rotational rate the top/log can't traverse the 10 or 12 feet eavestrough to ground height staying parallel to the ground. It's going to rotate some.
At the same time the top/log CofG has achieved a horizontal direction component in the correct direction - away from the shed. But it wants to push against the hinge/spar top all the way to horizontal during the fall. With a decreasing amount the closer it gets to horizontal (short rigid stem, not 150' conifer spring pole with resonance movement).
So the question becomes you want to utilize the horizontal velocity you built up, but ideally you need the top to depart before horizontal and the contact force/push doesn't want that to happen.
Can an aggressive Humbolt (or?) convince the log/top to depart before horizontal. Safely?
Or like the farmer's road directions " Well, ya just caint get there from here..."