I have met more horses that Wintec's don't fit, than horses that they do, despite the changeable gullet. The gullet is only a single aspect to the fit on the saddle. Some saddles, will not fit some horses, no matter how many adjustments are made to it. Not to mention, that you will find that you will enjoy one saddle on one horse, but hate the same saddle on another horse!
I would strongly advise that you wait until buying a horse, to buy a saddle.