Bah, there are very few occasions when I would play a 2-3 zone with the current engine. The truth is that it does a poor job of defending any type of attack. In fact, on some occasions I would be willing to use a 3-2 zone to defend an inside offense.
If you have good outside defenders and average inside defenders then I would suggest playing 2-3 zone unless you are sure your opponent is going to play an outside offence and has a weak inside attack.