How practical is ACB for money saving purpose?

Stun will always be worse than ice for saving money, simply because of 90% vs. 100% success rate.

It does get better with ACB because you don't have a near 1.5 second cast time. Stun only lasts about 2-3 seconds so there's not as much room for failure.

I usually used CB to stun and then only attacked with Powerstrike. If you leave monsters alone, stun lasts anywhere from 4 seconds to when you leave the map (I've seen both Elder Wraiths and Skelegons stunned permanently)

I don't remember perma-immobilized mobs. I actually timed a "perma stunned" Dual Ghost Pirate, and it turned out to be roughly 2.4 minutes.

If you employ ACB correctly, it will save you a lot of money. But it can't quite beat Ice Charge in terms of getting the monsters to STFU and not attack you.

So yeah, what Stereo said xD