Right indeed, but I never considered this possibility, since I didn't want Imoen to be of that high level (I was a mage myself, didn't need her spells at all. I was really sorry that her rouge abilities couldn't be improved, though
On the other hand, Krunchy is right, too! Imoen is waiting, being tortured to near death... (of course we know that she'll be in the same state no matter when we get there...