I think what sets the HO'er in a bad position is the greed that comes with it. If I am merging and watching angles I am in "Observation, orientation" and constantly making decisions to put my plane on a firing solution to where he will hopefully be through continuous orientation. When someone stays in the "action" (pulling the trigger) phase without proper orientation to make a good decision (where I need to angle my plane, throttle, etc...), they put themselves behind the curve. I have almost gotten into a bad habit of offering a shot to my opponent to entice them into a bad decision. It works many times as they stall or place their plane at a bad angle but when I encounter a very good stick I end up in the tower in less then 2 seconds. They don't fall for it or they don't miss the enticing shot which leaves me behind the curve.
So I agree that if you dodge the HO and put your plane at a poor place in space and angle and the HOer stops the straight on attack and breaks into a normal merge he would have the edge, BUT if I can practice a merge that both gives me good placement for a merge AND makes it difficult for the HOer to put well aimed fire on me it will give me the edge as long as I don't deviate and break. Filth has a very unusual merge that does this I think.
Everyone goes through this cycle of Observe, Orient, Decide, and Act. The person that can go through it at a quicker tempo usually wins.
Search John Boyd for more interesting reading on the OODA loop. We have adopted this teaching for law enforcement with very good results.
