I'm often using it as in English Jung typology sources 4-letter type notation is more known. So when someone new reads the forum it makes easier to understand. Also, many ones here seem to use MBTI's notation for 8 Jung functions (Te, Fe, etc) as it's comfortable.
On Russian language Socionics sites I'm using Augustinavichiute's notation with 3 letters as it's what most common there, while MBTI books are lesser known.