In my experience the two fit quite differently so it may be best to try them both and see which fits your horse best. Personally I prefer the Thorowgood to ride in, but I'm sure others prefer the Wintec
Wintecs I find are very uncomfortable to ride in, and seldom fit the horse (from my experience, I find they are often used on wide flat backed cobs and it's a poor fit). Just realised that point is moot anyway as you're having a saddle fitter
I had a Thorowgood and my saddle fitter said it was a really bad fit and swapped it for a wintec. She said the 2 are very different, I liked the Thorowgood best though
I wanted a synthetic, had kind of decided Thorowgood was the way to go but the Wintec 2000 was the only one that fitted both me (long legged 5'10") and the horse (16.1 short backed couldn't take an 18" or any of the thorowgoods)
My advice would be to not get your heart set on something and buy what's right after fitting.
TG everytime if it fits your horse...seen 6 horses in wintecs and five of them had white patches and sores and 1 looked crippled....might be old versions but the shape didnt seem to fit at all, havent ridden in wintec but find the tgs very comfortable i have the t6 high wither and do dressage sj upto 1 mtre and xc 90 cm in mine with loads of security
I have a wintec 2000 and the mare i share loves it. Brought it to try as her old saddle she would not move in. It was second hand cost me £60 and she loves it. Tried it on the other horse i share with saddler there and he bucked reared and really didn't like it. I think if they fit they are great saddles but you have to accept they are not one size fits all which many believe. They also are an acquired taste to ride in as they do feel different to a leather saddle.