1- There should not be rules about how people equip their ships.
If the weapons are there, they are there for a reason.
Now, concerning how they should be equiped for the sake of correctness and coherence, that's another question...
In this point of view, people could mount fighter weapons, cruiser weapons, gunboat weapons, whatever other stuff appart from BS weapons in their Battleships.
That is a weird thing to do and might unbalance things alot.
Why?
Perhaps the problem is exclusively in the BS class weapons. Most of them are not up to Batleship standards.
People will always equip the wrong stuff in battleships because they are not happy with the battleship weapons available out there.
I bet if those weapons were really hot they would not want something else to equip their already pricey vessel.
Even for those who like to be diferent, having something other than BS weps on batleships should be making them less powerful - wich leads to disadvantage in combat and possibly searching for batleship weapons to equip, only, in this class of vessel.
Consider that no one mounts cruiser weapons on fighters, or perhaps bs weps on cruisers. It is as ridiculous in the same way as mounting weird combinations of non-bs weapons on a batleship should be.
2- As for a price increase in either weapons or any kind of ship class, I am against it.
I already had a hard time getting a train. That's 20 mil and only got there with help...
300 mil gets you just enough to pay for a system... leting squadron stuff (support for other players in the faction) and other character funding aside...
3- Sticking to the official thread about 4.81.
Imho, Batleships should only have harder shields. I explain.
Since some weapons are going to disappear (read: novas), Bomber Fighters could be equiped with a special shield blaster weapon.
This way, while keeping the hull as it currently is, we could get as realistic as we can see in the Single player fighters taking down a batleship.
We also keep the fighting time it takes to bring one BS down.
Other things have already been told by Igiss.
BS weapons will possibly have longer range, faster refire rate.
We should also be either having a more powerful generator, tweak all power-hungry weapons or both.