I like your class write-ups for the specialty mages. My one issue with the class creation rules and making specialists this way is your illusions (or fire spells or ice spells etc) will be cast at 2/3 caster level - so they're actually worse than a regular mage at their specialty. I believe when I was creating something like this I limited their spell list (like a cleric) to keep them in a theme but gave them full caster level in their narrow speciality - so a pyromancer's fire spells are calculated at full level rather than 2/3 level, non-fire spells on their list are cast at 2/3 level, and mage spells off their list they simply can't cast at all.