I hadn't put much thought into admixture, having not that much experience with it. Frostfire could be very, very fun. Another thought would be to run Fire/Elec or Frost/Elec and take Stormcaster to 5 to make every spell into a Dual Threat. You've given me some stuff to ponder. As per earlier in the thread, I was thinking of just running a Searing Spell Fire Evoker.
I've decided to accept a certain amount of dual progression for one build at least. I really wanted to avoid it if possible. However, I've decided that 1 level of Binder + 10 Anima mage will give an Enchanter a good power boost, flexibility, and fits really well with the concept. Net result: Binder1/Wizard3/Anima Mage10/Mindbender1/Master Specialist 4/Shadow Adept1. The binding progression only ends up at 13, with the Improved Binding feat. The build only loses 1 caster level, so it works for me.
I'm toying with replacing the Shadow Adept level, but it's nice to get 4 feats for the price of one. Mindbender is obvious and fluffy. MS4 helps shore up a small weakness with its minor Esoterica. The build favours Charisma somewhat, which again fits with fluff, but isn't too dependent on it so I don't get too MAD. I would likely go with the UA Social Proficiency Wizard Enchanter variant, as that gives me some nice social Skills, and since I don't hit Wizard5, I don't lose the free feat anyway. Anima Mage is plenty strong of course, and some free persisted spells could really help one of the "weak" Wizard specialists. Thoughts?
Edit: I've also updated the OP to list the current builds I am running with. I have 4 largely statted out, and 4 that are still up in the air.