Board Thread:Questions and Answers/@comment-19203513-20150927074914/@comment-26574811-20150929140950

AS+ advantage over AS:

1. less plane loss.

2. higher aerial phase damage (with same # of bombers, partly due to 1. and partly due to scout plane contact)

3. better chance for barrage stage special attacks (Arty spotting/ double attack)

4. deny enemy from spotting or contacting

5. less damage from enemy aerial attack, similar to 1. and 2.

So it is generally recommended to have AS+ as long as it's possible. If it's for the last (boss) node and having AS+ would mean very little firepower from carriers (or simply impossible), then AS would be acceptable. Otherwise always go for AS+ as much as you can.