I think the biggest argument is that the blast marker also downs a shield, but given that this is minor due to the fact that it would have to be facing off against something with comparable range (most ships of which, if not all, dont have the power to really take advantage of it) that i dont see it being that much of a down side.
The dorsal weapons were deemed to be inferior to a comparable battleships dorsal lance battery. Of course if the ship is given an adequate price for said weapons I dont much see the point in changing them to 9 and then boosting their points. If the Apoc is adequately priced with 6 Dorsal wb then leave it, same for the Vic.