If you are changing some auto-succeeds you should change them all, shouldn't matter "how powerful" an auto-succeed is relative to another. Is seeing through Illusions wicked awesome compared to auto-detecting lies? Most of the time, but it depends on the campaign.
Now, I have this idea where evocation spells that deal energy damage can just deal whatever kind of energy damage the caster wants. Is this too powerful? Thoughts? I mean that a 1st level Wizard could cast Shocking Grasp but decide to deal cold damage with it today. Wizards would likely have to prepare it as a Icy Grasp, Sorcerers could maybe just on-the-fly, spur of the moment, Icy Grasp. The reasoning behind this is that NOBODY is going to waste spells known on all of the different energy types for all of the orbs, and balls, and grasps, and rays, and bla, bla. They're just going to pick the best one. So why not take it one step further and say that everyone always has the best one?