One of the issues with the Ability Score Array is the power of saving throws and the weakness that comes from not investing your level ups when you other Ability Scores are raised. One Example is a Wizard who raises Int and then raises Dex/Con/Wis if they're not using Str or Cha. If the Wizard wanted to use Cha for skills then depending on how effectively he uses and invests in those skills determines if it was a better or worse option.
I don't think wanting to raise Str or Cha should ever be balanced against the defensive prowess of a saving throw so I had an idea on how to change that.
My idea starts off with the idea that Strength, Intelligence, and Charisma correspond to a saving throw. Str for Fortitude, Int for Reflex, and Cha for Will. In the Alternative Ability Score Array Strength combined with Constitution and Charisma gained Will Saves. Int could be considered using your powerful mind to react/predict danger.
So my idea is that the alternate stat gains +1 to its saving throw every 4 points, so 14,18, and 22. It's limited by the natural cap a character could have with the same stat at that level. So since 18 Dex is +4 Reflex to get +4 Reflex you would need 18 Int for +2 Reflex and 14 Dex for +2 Reflex.
Another thing to take into account is that only one stat could every reach max potential so an 18 Dex Character can only reach 16 Wis for +3 Will the cap remains similar for the 18 Int Character.
With this system a max stat of 22 without the +2 stat item Dexterity at level 20 would be 22 for a +6 reflex so 22 Intelligence and 16 Dexterity would be enough to reach cap. With a stat item placed into Intelligence the cap would become +7 reflex then requiring 18 Dexterity. Dexterity only raised from 14-18 with this system allowing 2 level ups to go into other stats.