We tried one, well, my saddler ordered one for my flat backed sports horse mare who needed an XW gullet. It went very curvy and banana shaped with the XW plate, so it was returned without actually going on her back.
I know someone who sells them so have seen a fair few, they look nice for the money and as far as I am aware they fit a variety of horses, I prefer the total leather ones to the part synthetic ones but I am not a lover of synthetic saddles anyway.
My son has a JW close-contact leather jump saddle for his Anglo-arab x cob. The horse is 16.1h, medium wide and has moderately high withers. It fits well and my son and the horse find it comfortable. I think it is like riding on a board - but then it wasn't bought for me! The saddle is now around 10 years old and has worn really well despite lots of mileage - he usually uses it for hacking and it has been round many eventing courses! It was good value for money and I'd be happy to recommend them.