Magnepan "3 series" differences?

Interested to know if there are dramatic differences in sound quality between the different Magnepan "3 series" speakers - e.g: IIIa/3.3/3.5/3.6. I've never had the chance to compare the different models, but wondered what - & how dramatic - the sound quality differences were?
Can anyone offer a comparison?
Go to the planar asylum, someone just gave an excellent answer to this question. (Perhaps you're the one who asked it?)
Unless I am mistaken, the question on the planar asylum is about changes in design. I am more interested in how the different models - in the 3 series - sound compared to one another. In other words, I am looking for feedback from people who have heard two or more of the 3 series Maggies.
Perhaps you could ask that question there? There are bound to be people who have heard all or most of them. Or look at old reviews, they'll typically point out the sonic changes from previous models -- the one I remember is that they moved the mylar to the front to make the speakers more "alive" sounding. Also, in general, quasi ribbon drivers are more transparent than wire ones, and a better match for the true ribbon tweeter. I think you'll find in general that the main weakness of the old wire Magnepans is the midrange.