Just for the fun of it, let's get back to the original question, which was, if you consider the "HO" a valid 'maneuver', then how do you perform it successfully? Forget that long range probablitity says you will only be successful 50% of the time.
OK, first rule is, if at all possible, have an aircraft that has a significantly greater weight of firepower than your opponent. The FM2 head on with a Niki or Tempest probably can't even be computed high enough to qualify as a poor probability of success.

Second, balancing the first rule as best as possible, have a responsive aircraft, in particular, one that lends itself to superlative nose control. The best one that comes to mind is the Spit.
Now, how do you perform the maneuver to best advantage. Fly head on towards the bad guy, just before he fires induce a little angle off so that hopefully his first burst will miss, but you'll pass very close. Then just before you pass, you snap your nose towards the bad guy then away again so as not to collide. Remember to pull the trigger as you snap towards him. You splat him right in the face.
The Spit is marvelous at this, even if it's weight of guns is a little light. The Hispano 20mm's are effective if you hit. Get good at this maneuver, and on an even basis, your success probablity will go up to about 51%. Of course, you'll take a lot of deaths getting good at it.

I'm not an advocate of just HO'ing everything in sight, but if you're out numbered in a turn fight, you often find youself face to face with a bandit re-entering the fight, and you have a good opportunity to reduce the enemy numbers by one with a quick HO. This maneuver will do it... sometimes.