The tweeter in the Sasha 1's is the older inverted titanium tweeter. It is good but can be a little harsh/edgy with some material and in some set ups.
How do I know?
Because i have owned W/P 7's for 17 years (same tweeter).
Didn't really recognize the edginess until I bought Magico A5's and Joseph Audio Pulsar 2 Graphene's. The tweeters in both are superior to the older Wilson unit, lower in distortion and yet more transparent.
The Wilson needs a slightly warm amp but something that can handlle low impedence.
Good luck!