As I said, it depends on the horse. The owner who rode bareback tried literally hundreds of saddles on their horse before giving up. They didn't have the $6000+ it costs to get a saddle fully custom made here - we're talking from the ground up, tree and all - and nothing off the shelf would fit no matter what they did to it. No standard tree saddle would fit that horse. Not even a cutback would fit that horse. The owner who rode in a custom spent a LOT of money having their saddle made... they didn't say how much and frankly I don't think I want to know.
Now, MY horse is about as wide as he is tall, but has withers I would class as moderate. And his back is like the roof of a house, it's not flat at all. His backbone sticks up a little bit even when he's fat and has good topline. So, a standard tree saddle fits him quite nicely. He's been in anything from medium-narrow (with previous owner, when he was first back under saddle after she rescued him, so he was still a bit skinny and lacking a LOT of muscle) to what he's in currently, a wide... extra-wide in my dressage saddle but that saddle is a size narrower than the plate that's in it.
Incidentally, my other horse is quite flat-backed (odd for a TB) and I am SO lucky she doesn't have high withers because once she's bulked out some she may well go up a gullet size or two... which will be extra wide or even xxw. But you never can predict what their backs will do, who knows, she might not get wider at all... she might stay her currently slender self, and with maturity, end up taking a narrower plate. I don't think that's likely, she's 2 and is beginning to bulk up.
I have had a VERY flat-backed horse, his back was dead straight from just behind his wither right the way to his croup. Could have put a ruler on his back with no gap at any point in its length. And he was quite wide. I couldn't find a jumping saddle or even an all purpose that would fit him, so I ended up buying a dressage saddle, same dressage saddle I use now (flocking modified to fit) on my gelding, and to get my filly used to the tack. My primary discipline is jumpers, so there wasn't a lot of point in me buying a dressage saddle, except that there was literally NOTHING else that would fit the horse I was buying for at the time.
I haven't actually had my hands on a Wintec or Bates Wide, I'm just going on what I've been told by a few people I know who have them.
Last edited by blue eyed pony; 09-19-2012 at 02:48 PM.