Since my name was brought up I think I'll make a comment or 2!
First I dont call it a HO,it's a John Wayne merge to me were you come in guns blazing with no thought but to kill the other guy! Many have little choice but to do this because they have found out to fly any other way but to fly the gunsight at the enemy.
After that first merge AFAIC anything goes,an acute angle frontal attack is fine as long as you dont get infront of the enemies guns,but if I find the enemy turning into my guns and I have a shot you can bet I'll take it. They way I shoot I need to shoot a much as possible to get hits so it would be silly of me to pass up any shot.
Alot dont know or remember that back in the day WB's had a cone of silence,a frontal area where your bullets had much less effect and it made most frontal attack a waiste of bullets,this is where all the Ho,no Ho stuff came from and now it's seen as bad form. In a duel,I agree it is bad form but in the MA where it's a freeforall I dont see as it being unreasonable thing to do! Again alot of players have no choice or even those who do know better may have to do it just to stay alive and in the fight.
Then there's the wiley old vet who know that a quick burst before the merge can upset the enemy enough to give that vet a huge advantage in the fight.
Personally I dont judge how a player flies,what they fly or how they want to play. My only hope is to pass on a few tips to help players have more fun and maybe gain some skills that will gain them confidence enough to not resort to a John Wayne merge!