Adam isn't giving the complete picture.  When SB 21 was being debated,  Dermot Cole and several other pointed out that at low oil prices, the state would be paying out more in tax credits than it would get in production taxes. This was dismissed as scare mongering by the proponents of SB 21. But that's exactly what happened.

Under ACES the state shared paid significant tax credits at lower oil prices and received a significant reward at high oil prices. Under SB21 the state still pays significant tax credits at low prices, but Alaska doesn’t get the increasing rates at high oil prices.

Heads the oil industry wins, tails the state loses. 

The purpose of repealing SB 21 is not to go back to ACES, it's to fix the inequities of the current tax scheme.