HOing means
Head
On. It takes 2 planes to perform a HO shot. It's a completely viable shot. It's the most risky of any shot as your opponent has guns on you as well however it's also the easiest shot in the history of aerial combat to avoid. You can turn in literally any direction and easily make them miss the shot. Someone will claim a HO shot when it was just a high deflection angle but that's not a HO shot as "HO" stands for "Head On". If it's not nose to nose, it's not a HO. I have been unable to determine why people complain about dying in a HO shot when it's such an easy shot to avoid. You can only die in a HO shot if you intentionally flew into your opponents guns. If you die, it's no ones fault but your own.
There is no rule anywhere that says you can't take HO shots, some people just don't like it. It's actually a pretty good tactic to use in planes like the Mossi, 110, or 410 since these planes have tons of cannons in the nose and can take a bit of a beating. If I'm flying my Mossi and you try to go head on with me in a zeke then you bet I'm going to shoot!
If you're getting hate PM's then good for you! It means you out fought your opponent so well that it hurt their ego
(also, if you don't enjoy reading PM's like this you can use .squelch NAME to mute them).
If you're in a slower plane defending against a high speed BnZer then use your biggest advantage, maneuverability. A zeke or niki are more maneuverable than most BnZing planes. Your objective in these kinds of fights is to stay alive long enough to either get up to their altitude or they make a mistake and come down to your altitude. If they aren't making a diving pass at you then take the time to level off and gain speed if needed and then go into a shallow climb away from them to start slowly chewing away at that altitude advantage they have. Remember to keep enough speed so you can maneuver when they make an attack run. When they come in, use you superior maneuverability to turn into them, point your wingtip at them, and make them miss either by your initial turn or pulling up into the vertical or diving a little as they get into gun range. High speed BnZing planes tend to not turn very well and struggle to readjust their attack approach, especially against a slow (or medium speed) zeke or niki. When they miss, if they go back up, level off, regain your speed, and then continue another shallow climb. If they make a mistake and waste their speed advantage by turning, or altitude advantage by continuing to dive, then reverse your turn into them and go on the offensive