I can't stand older Isabels, I feel like my pelvis is being crushed and I am clamped to the saddle. Maybe good if you're a beginner on a school master, but trying to ride a green horse as an experienced rider, I find that saddle near impossible.
The Wintec Pro's are better, and give me much more freedom to move, though I still get some pain from them, I just don't suit Wintec's terribly well.
I have ridden in a new style Bates Isabel (the leather version of the Wintec) and liked it hugely more than the old style. The new model came in I think at the end of 2010/early 2011. The saddle gives much more room to move, less bulk under the leg, and a shorter tree. Still not one that I'd buy, but I can ride in one without feeling like my pelvis is going to shatter!
If you take one piece of advice from me - don't go and buy an Isabel without first riding in one, and trying it on your horse. They are very different between horses, and some people love them, while others like myself hate them!