Well, unless you had something interesting to add re: Freud we don't need to. I think the ego/id/superego model, or at least how I've conceived of it, is quite fascinating nonetheless.
Basically, I agree with what you just said about I and E, but I don't think MBTI uses that same definition. They use a -based on the impressions already present to the subject? or based on impressions directly seen in the environment? e.g. Fi is seen as being like a moral compass, but Fe is seen as reacting directly off of what is happening in the situation. I don't think this is what is meant in socionics by the terms.
Basically I am supposing that how Socionics describes things is correct, and how MBTI is is correct too, and seeing what this implies. What it implies is that MBTI i functions always map to creative and role, but e functions map to base an vulnerable, and similarly socionics i maps to MBTI auxiliary tertiary, socionics e maps to MBTI dominant and inferior.