Arcane Keeper becomes the best specialty for any one trying to maximize saving throw dcs. I would probably change spell casting expert into something else. Mind you Save DCs are generally lower across the board, that specialty lets me save the equivalent of 4 CHA to put into another stat, and still get a 30+ dc at level 20.
Yeah, keep in mind that Lore Keeper got erratum (
which you can see here.) The way it breaks down, Spellcasting feats
in Spycraft appear to be worth an extra half point because of it's extra benefit. That being said, I'm surprised how much cheaper paired skills are in Mastercraft compared to Spycraft.
Past that, I think even your revised Arcane Keeper is the hands down best specialty for a mage.
IMO, obvious choices are a bad thing, and this specialty contributes to every aspect of the mage. I think
Celebrated is heading in the right direction of a
distinguished mage, as opposed to flat out
better.