As Death implies, the weapon that does the most damage isn't necessarily the best one -- Particle Cannons are better in other ways (especially range). Remember that when Wing Commander II came out, the Particle Cannon was the cool 'new' weapon (the punch of a neutron with the range of a laser)... the newest Confederate fighters had them, while the neutron gun was being relegated to turrets and Kilrathi ships.
Wing Commander games also kept trying to suggest that the neutron was being phased out entirely... Wing Commander III even tried to kill it entirely, but it wouldn't stay dead.
I don't know if F-44H is a designation that actually gets used anywhere, though.