Its been a few years ago since I had a Wintec but the one I had came with the measuring thingy. Maybe they are selling them now?
Its really worth it to get the measurer. It takes the guess work out of which to use. It seems like it was fairly easy to change the gullet, but I had to do some modification to the screws as they started pulling throught the material if you change it too often. I just added some small washers. It was a comfortable saddle, as far as durability maybe someone else can give you advice. I only had it for about 1 year.
"Until one has loved an animal, part of one's soul remains unawakened..."
- Anatole France