Oh man, this battle system sounds awesome. Very VP2-ish.
Here's hoping that in order to do all actions, you have to have an ATB charge. So that if you use say...Attack -> Attack -> Defend, in order to do another action, you have to have stocks. Whether it's defend, attack, use magic, or even use an item you have to have a stock. This will make your actions actually count in battle, make the game more tactical.
Make the enemies more tough like what is seen in the remake for Final Fantasy IV, give players the ability to move while in battle for tactical advantage -- not just for novelty like in FFXII, evolve upon the environment interaction in battle that FFX started and I think this battle system has potential.
So long as it doesn't have too much of an easy difficulty it'll all be good I think. One problem I have with games like FFX is that...they have a lot of great ideas, but the games aren't challenging enough to make use of them. Up the difficulty, S-E!