I know this discussion has branched out a bit, but as an answer to the HO question.... I find that when I'm in a 'furball' and may have 3 or 4 enemies within distance to engage, and an enemy turns into me or puts me in a situation where I cannot avoid the HO pass, I always fire at him as he passes, and I'll tell you why.
Above anything else, I have no guarantee that he WON'T fire on me, so if I just fly by, and he fires, I just sit there and take it, then he is still flying while I'm floating down in a chute minus a few kills probably. I came to this decision a while back, and I have to say that I don't regret it. Now I don't go looking for HO shots, and I try to avoid that pass if I can, but if it comes down to it I will fire.
If I knew who the enemy was, that would make the story completly different, as if I knew the guy was a 'regular' or a veteran of sorts, I would go cold on the merge and maybe dogfight him depending on the situation. Maybe this gives you another perspective...
--Howitzer