I'd like to know this, as well. For 20 aa's, you think they'd tell you exactly what it does. 10% increase? Not worth it. 20%? 50%? I'd definately do it for 50%, but I'm not gonna waste 20 aa's to find out =P.
In general, I think this expansion is all about making people play a lot more without making them more powerful. I think Sony is afraid of making someone with 400 aa's significantly more powerful than someone with 100.
Soooo, they make a bunch of new aa's, and they don't tell you exactly what they do. Then, you spend 20 aa's, and realize it's something like a 10% increase.