How practical is ACB for money saving purpose?

Does ACB really save you money? As I recently maxed charged blow on my WK, I have been playing with it for abit. It's true that the stun is uninteruptable by any attack, but it does get canceled if you fail to stun the mob with another charged blow. Resulting in being hit by mob's magic attack. And it's happens quiet often when it comes to a mob or 4-6 that I'm feeling the stun doesn't really save me that tons of money on pot.

Does this get better as you get ACB? Or it's just the way it is?