OK, here goes:
1.0 - 1.1: There were changes to the crossover as well as new binding posts.
2.0 - 2.1: A completely new crossover was implemented. It raises the impedence of the speaker as well as the efficiency up to 90db. The 2.0 was a bit dark sounding and with the implemented changes it became closer to the 1.0's.
2.1 - 2.2: There were changes to the crossover as well as new binding posts.
3.0 - 3.1: A completely new crossover was implemented. It raises the impedence of the speaker as well as the efficiency from 86db up to 90db.
3.1 - 3.2: Internal cabinet improvements. Better bracing, damping and doping. Improved tweeter. Internal wire is upgraded from Supreme Reference to Grand Reference.
Hope that helps.