James63 - I did not have a chance to listen to the Sophia 3.
However, based on my experience with Sophia 2 and Sasha, i can tell you that the biggest difference for me is in the HF department. Sasha tweeter is noticably different to Sophia 2 tweeter and much, MUCH better IMO. Sophia's 2 tweeter sounds grainy and 'hot' in comparison, wheres Sasha tweeter is very extended, airy and oh so smooth.
It is a bit difficoult to compare the midrange microdynamics, since Sasha is higher sensivity, which almost always makes the speaker to sound more alive, but it sure has more body.