Personally I don't care for the wintec or the abetta western saddles. The wintec ones just feel like they are made of cardboard to me. They make really nice english saddles, and I heard that their aussie saddles are really good too, but I have yet to be impressed with their western saddles. I am not a fan of cloth saddles like the Abetta, plus I felt like it positioned my leg way in front of me and I was constantly fighting the saddle to get my leg under me, however that may just be me.
My TB was built exactly like your horse, high withers with a dip behind them. I never did find a western saddle to fit him properly (which is why I bought the aussie saddle). Not only do you have to consider his high withers, and how narrow he is right now, but a lot of western saddles are made for QH type horses who have more of a flat back, and it looks like you may run into trouble with briding on your horse.
RH Queen O Anywhere "Sydney"
2009 Sugarbush draft