Just reached Caio Duilio, and here is my opinion on Italian AA.
When you first get to GB in your Mini BBs, you will feel like you are gimping your team with such a worthless bb that only has two mounts for dual 12s with horrible spread and range. However, the AA is excellent in certain situations.
Some of the Italian BBs, as mentioned before, have 7 T slots per side, which is alot of AA shells you can throw in the air.
That would be 14 barrels per side with some of the smaller dual AA guns, and 7 6in EOC AA shells whch is what I ran.
Oddly enough the 6in EOC shells that owned in GB, are great for AA if you know how to use them. The biggest drawback is the highest angle of 25. However these pwoerful shells can shoot mosst planes down in 2 hits, and some with one salvo.
So the best time to learn AA with Italian BBs, is the first BB. Because that is all it is good for, with such slow speed and two mounts.
Max your 6in EOCs at 25 angle, and see the distance where the go "poof" and set your distance where you can put a protective cloud next to your higher BB4-bb6s. Hell you might even get a chance to use your two R mounts. =P