I also have comments and questions that have dragged me out of the woodwork to finally post. Are you keeping the existing calculation and simply adding the spell school to it or are you considering something else?
I understand why you are changing the acid portion of Draconic to Conjuration bonuses for Sorcerers, but as proposed this is also yet another potential nerf to Warlock casters using GOO pact. There are not enough feats to allow both an Evocation and Conjuration focus and still enable a warlock caster to be relevant in high difficulty end game content. Why not make the calculation for nuking abilities in this tree the higher of Evocation or Conjuration bonuses to enable relevance to both Sorcerers and Warlocks? Does Warlock really need another debuff?
Since we are considering leveling out power imbalances let's talk about how under powered Fey pact is relative to the other two with the Ravenloft belts. The argument that not many mobs have resistance to sonic doesn't hold up when many mobs are also not resistant to acid and Tiefling Improved Scorch removes fire immunity. If Fatesinger's Harmonic Resonance proposed "Attacks have a chance of building up Resonance ..." refers to non-spell damage, why don't we change this to something actually relevant for sonic casters? Are we planning on adding equivalent gear for stacking sonic spell power bonuses instead?
As a long time DC caster player I am certainly in favor of the Magister changes. Currently, you have to gimp a non-Shiradi caster wizard to make DC relevant in mid to high reaper and a wizard doesn't contribute much DPS for mobs outside of his or her DC. With all of the death warded mobs and champs, the high DCs of Sharn, the relatively low negative healing available to PMs, and the low hp and armor restrictions, the DC and Arcane Tempest updates will help keep things balanced. Many forum posters have tons of past lives and gear from raids that basically no one runs anymore. From what I see on Ghallanda, a good chunk of these players prefer to group with comparable players and everyone else is left in the dust. While the Magister changes may make these already OP players more so, they do help level the playing field as well.