I disagree about the N1K2's Type 99 Model IIs. While their RoF is not very good on a per gun basis, as modeled in AH it is the second hardest hitting 20mm cannon. That coupled with its insane amount of ammo is what makes it so dangerous in spray and pray situations. The Type 99 Model IIs of the N1K2-J and A6M5b hit with 98 or 99% of the power of the Hispano Mk II 20mm and, unlike the Type 99 Model Is of the A6M2 and A6M3 also have decent ballistics roughly on par with the MG151/20 20mm, SHvAK 20mm and Ho-5 20mm. The Ho-5, in comparison, has a much higher rate of fire, but it is also the lightest hitting 'good' 20mm cannon by a fair margin, meaning individual stray hits are not as likely to cause catastrophic damage. The lighter ammo load coupled with the much higher RoF require the pilot to be much more judicious with their shooting. The Ki-84 is the better duelist, but as a brawler there are strong points in favor of the N1K2-J and strong points in favor of the Ki-84, but firepower is most certainly on the N1K2-J's side.