Gunboat primary speeds are getting nerfed by almost a third to approximately 1000m/s. If gunboat cerbs, which have a speed of 900m/s are any indication, they'll be useless against fighters and out-classed by cerbs against other gunboats.
Solaris turrets are pretty useless against snubs as they are, since they lack the damage to do anything against snubs that aren't loitering within your range, and are worse than useless against other gunboats.
Cerbs can only hit snubs when they're sitting still for you within 200m ish from your ship, and drains your core too fast in anything but a heavy gunboat - and are pretty tough to hit other gunboats in, unless you're on its tail within 500m (300m if the gunboat can actually maneuver, and less than that if it's one of the many light gunboats that can kite all day) - which is fine if you're flying a heavy gunboat, since you can normally catch them slipping up so that they're trapped within your killzone as you keep on their tail.
Razor/pulse setups are suicide against other gunboats with cerb/solaris/primary loadouts, but you can get lucky and instakill fighters (and maybe bombers if you've got enough razors hitting at the same time).
There's a new antifighter beamweapon set to be released for the next update which is supposed to have higher energy cost than solaris turrets, but nothing can really be said about them until the new update comes out.
If you're planning on a loadout JUST for this mod version, go with primaries. If you're asking about the next update, then your guess is as good as mine, though it looks pretty grim at this point.
