If you want to stop people using fighter turrets you'd probably (not to sure) have to make the BS turrets unmountable.
At the moment most codename weps do similar damage as Cap-ship turrets but don't use half as much energy. Personally cap-ship turrets should be more powerful then codename weps.
Has anyone noticed that most VHF's have class 10 turret mounts but there are no class 10 turrets in the original game.
(on-topic)
Personally if I had a liberty dread I'd have 2 or 3 Britonia BS missile turrets and mount nomad guns on the rest. Yes nomad turrets refire's are bad, but they do more damage then any other BS turret. On the plus side the low refire means you can keep firing for longer.