Actually there is a
Socionics thread but it didn't get much interest. It's probably because Visual Identification makes Socionics an unpopular theory. If you discard the V.I. crap and figure out how they define the J/P classifications, Socionics can be interesting.
A lot of Socionics proponents claim that MBTI and Socionics can't be compared because the functions are defined differently. The problem is that the function descriptions seem similar for extraverted types (type descriptions are similar to MBTI type descriptions) but get incredibly confusing for introverted types (type descriptions are similar to MBTI type descriptions, but what was once attributed to NiFe is now attributed to FiNe, etc).
Socionics does seem to have the best descriptions for intertype relationships if you know to switch the J/P for for introverts.