The T3 battleships are mostly a waste of resources, missile subs are much better, assuming your opponent is still around by that stage. The pro players never bother with anything bigger than a T2 destroyer.
Pro play is boring though

Got about 8-10 friends and we love FA, though we're not fantastic at it. We all play long, drawn out battles either against each other or agains Sorians, approaching the stage where we can almost stand toe to toe with AIxs, as long as nukes are turned off! We mess around with silly strategies, building a huge army of SCUs with the personal teleporter and all the weapon upgrades, then teleporting them all into the opponents base next to their ACU, as cybran creating a ton of SCUs and giving them the two stealth upgrades which makes them invisible to radar and vision, then taking out their omni with air. Then just walk into their base and he can see you shooting, but can't see what's doing it and can't target.
And also building up giant fleets of battleships. Sure it may not be super efficient, but they make stuff blow up really well
