I've had W/P 7, MAXX 3 and Alexia's in my system. Just going by memory, but:
W/P 7 - these were my first Wilsons. All my previous experiences with Wilsons left me running for the door. Somewhere about the time of W/P 7 and the Sophia, the Wilson sound changed for the better. The speakers were more coherent and listenable. They were still using the Focal inverted dome tweeter, but it was more subdued. Still, extended listening sometimes gave me headaches, but the transparency and detail retrieval made them especially useful for mastering.
MAXX 3 - these sounded exactly like the W/P 7 with a more extended bottom end. The image height was raised about a foot and there was a larger than life soundstage. Tonal qualities were the same as the W/P 7, but the midrange was a little more rounded with more body.
Alexia - this is another totally different sound from Wilson. With the new silk dome tweeter and sharing the same mid as the XLF, you can literally listen to these for the rest of your life. Tonally, it's a different beast. Bass has better transient speed without losing body and tonal character. Mids are as sweet as if you are listening to them with the best SET's. The top end goes to infinity with no hint of compression or edginess. They are transparent enough to use for mastering but not fatiguing. This is how a speaker should sound.