People are very polarized when it comes to Wintecs. They either love 'em or hate 'em; there doesn't seem to be much in between.
I LOVE my Wintec 2000 AP. It has the gullet change system, CAIR, and the seat is Equisuede, which is more 'grippy' than regular synthetic.
I have to laugh though, at what they call 'easy change' when it comes to the gullets. I haven't found it that easy to do, but the two horses I have it for are fine with the medium width gullet, so that means no changing it out every time I want to ride.
The 500 AP is a decent saddle, but I went with the 2000. Purely personal preference, and had nothing to do with the 500 being 'inferior'.
If your mare is bigger, you might want to purchase an actual wide gullet saddle. They do make Wintecs in wide width now, for the larger horses. The gullet change system doesn't make the saddle truly wide, just makes it wider than regular medium.
As far as I'm concerned, Wintecs are the way to go if you're set on a synthetic English saddle.
Other opinions may vary.....