I've had 2 Wintecs, never had any real problems with either so I've no problem with them, I would be lying if I said they would be my first choice (purely because I prefer leather to look at), but they're affordable and I find them comfortable and like the fact that they're adjustable-to an extent, I am perfectly aware that they cannot be made to fit every horse/a horse that has changed drastically in shape. On a similar vein, my Wintec GP which I had for Skips when I first bought him I had to sell because it stopped fitting him when he changed shape, he'd changed so drastically it wasn't able to be adjusted to fit him, that's fair enough, it served me well for the time it fitted him (a considerable amount of time) and I never noticed any problems in his back etc. He developed a lot with it.
I now have a Wintec Isabell dressage saddle for Soda. I love it! Very comfortable and well-designed. My only current gripe with it is that Soda has developed so much and broadened that it's currently too tight for him, so obviously I'm not riding him in it atm...but that's the beauty of the adjustability of it. Saddler has said it should be easy to widen whilst ensuring that it will still fit him.
What I find interesting is that there are numerous complaints about Wintec, but not many about Bates (I also have a Bates GP for Soda and love it!)...people seem to forget that Bates are made by the same company as Wintec and made in the same way, they have the same basic shape...without meaning to have a dig at anyone, I myself prefer leather to synthetic...but are the problems occasionally due to the fact that people automatically see synthetic materials as being 'cheap' and because they are cheaper, therefore 'badly made', whereas Bates saddles are fairly expensive (well, middle of the range for saddles) and leather so therefore viewed as automatically 'better' when they are in fact the same(ish)? I don't know and I'm not trying to be patronising, just genuinely curious.
I've had no problems with my Wintecs, what I have a real problem with is my Thorowgood which I personally find immensely uncomfortable and puts me in a terrible position whilst giving me no security over fences, or at all really. Plus I really don't think it is necessarily a great fit on high withered horses, despite the fact that it's advertised towards fitting them. Doesn't mean I think nobody should use one again. I'd just like to change mine asap, and will be doing so soon with any luck, but I shan't be calling for everyone to destroy their T4 saddles because I'm sure some people (many people actually!) love theirs, I just happen to think I'd be more secure riding my horse bareback than in that particular saddle!
But that's just me, it's not the opinion of a lot of other people. Unfortunately I think the opinions of a few people have influenced the opinions of the masses with regards to Wintecs, and the fact that they are advertised very much towards being able to fit any horse because they are 'adjustable' and some people don't have the sense to realise that does not mean one saddle from a 12.2hh pony and a 16.2 TB, when people find they are not 'that' adjustable they get angry about it! T4s don't fit all TBs but you don't see everyone complaining about it and vowing nevcer to use them again!
(I mean that with no disrespect to anyone on here btw, but just from everything I've heard/read, both on here and in RL).