It seems to me that the "strength" of functions isn't all that important, the role is much more important.
i.e. an IEI isn't an IEI because their is stronger than their etc., rather it is because is their base function (and is their role function, etc.)
So it follows that an IEI might have (or appear to have) weak /strong etc. etc., but because of their psyche's organisation they are still an IEI regardless.
What do you think?