This isn't technically Model A, but I want to open up a topic about a concept rolling around in my mind, which can be labeled "dichotomy shift", basically the idea is a type consists of four main dichotomies.
Say an SLE, ESTp is Extroverted, Sensory, Thinking, and Rational.
Dichotomy shift is considering that a shift in one of these dichotomies occurs either permainently or temporarily.
So ESTp --> ISTp
ESTp --> ESTj
ESTp --> ENTp
ESTP --> ENFp
I believe its possible to map fluctuations or changes in a person's type by these dichotomy shifts as well as reach a deeper understanding of type from analyzing these.
Consider some basic dichotomy shifts....
Introversion -- Extroversion
Sensory -- Intuition
Thinking -- Feeling
Rational -- Irrational
Consider what each could mean physically.
Introversion to Extroversion is a shift which implies outward expression of the self, it could designate something relatively minor over a small time scale such as a person initiating conversation with someone, or be an entire paradigm shift in a person's personality... i.e. the loner becomes a social butterfly after years of isolation.
By reverse consider Extroversion to Introversion. A usually outgoing person is isolated by themselves, or is placed in a situation where they are alienated by subculture, race, or other issues.
Consider Sensory to Intuition. Usually intuition works as a result of imaginary interpolation between sensory experiences.
An intensive run through of all the shifts could be notated but the general concept is presented here. Interestingly enough I think this technique can be used to understand the types better even if you don't believe in type change.
For example in MBTI an INTp is much like an introverted form on an ENTp and an ENTp an extroverted form of an INTp.
However in socionics this is more complicated.... is the introverted form of an SLE closer to an SLI or an LSI... interestingly relying upon model A and a jungian function perspective... the LSI would appear to be the introverted form of an SLE. One would except the LSI to share similar viewpoints to the SLE except have an introverted disposition towards them.
What is also interesting to note about this is that with this jungian function perspective that an introverted -- extroverted shift also requires a rational -- irrational shift. Thus providing an odd pattern or connection between Ixxj and Exxp temperaments and Ixxp and Exxj temperaments.
Duality and self-dualization provides a secondary connection between temperaments Ixxp and Exxp // Ixxj and Exxj...
Both the concept of duality and the introverted-extroverted shift can be used to understand a more dynamic and temporal concept behind type and how information elements move dynamically amongst each other.