If you had a 20 Charisma it would give you a +5 to your DC's, duration, and spell penetration!?!?! That is incredibly powerful. Sure, your character might not have a 20 Charisma, but you have to think about it. Toss in a Cloak of Charisma +6 and a Tome of Leadership +5. Enchanter starts with 16 Cha, adds Cloak to 22, and Tome to 27. He tosses in one level boost to even it out at 28. With the use of this spell, he increases the DC's of his spells by 9 and penetrates 9 better. That means he can land spells on creatures of his level with spell resistance with no chance of failure. His spell DC's creep up into the upper 20's if he has a good intelligence as well.
You have to look at how someone could best use a spell to determine its true effectiveness. Just because you would not try to squeeze every ounce out of the spell, does not mean it is any less powerful.
Assume the wizard from my example also has a 22 Intelligence from his adventures and items. That's another +6 to DC's. His 1st level spells would have a DC of 26, all the way to 34 for 9th level spells.
If your spell had no effect on duration or penetration, it would be far more reasonable. There is just too much in this spell and it can be worked too easily into a game-breaking power.