Besides various archetype changes/updates in the new AG, there are some significant changes that have been published for Ioun Stone resonance that may be of interest (and that I assume will be effective once the AG is officially added to Additional Resources):

Clear Spindle: The wearer can cast protection from chaos/evil/good/law on himself once per day (CL 12th). He can activate this ability as an immediate action, but doing so drains the ioun stone of its magic, turning it into a dull gray ioun stone.
[Previous Resonant Power: Protection from possession and mental control (as protection from evil)]

Dusty Rose Prism: +1 insight bonus on combat maneuver checks.
[Previous Resonant Power: +2 insight bonus on CMB and to CMD.]

Both of these items were significantly underpriced before. But, as with any change for PFS, if you no longer want the item in its newly-modified form, you can sell it at the Glorious Golarion Nerf Market for full price.

There were also changes to other ioun stones (including some changes that are objective improvements), but the ones above were two of the stand-out nerfs for relatively inexpensive stones that are widely used.