I own one and ridden now in quite a number. My barn has a lot of horses going in them. All are 2010 or newer so can’t speak to the older ones really… But the four year old ones look great and are ridden in by the pro on 5+ horses daily. The newer ones look good too. mine was delivered in May, I ride 2-3 horses 6 days a week and I am thrilled with its condition. A friend has a 2011 that is in excellent shape. Yes the leather is soft, and I don’t think I would make a habit out of hunting in it for example but for most everyone they are fine. I do hack in mine quite a bit and it survives attacks from wayward tree branches 
As far as the fit goes, I tend to think you can cause back problems with any ill fitting saddle no matter the brand. It’s only logical. Butet makes multiple different panels now, as well as tree widths. They can all be customized to you and your horse. While a certain panel did not work at all for my wither-y fellow a different one fits him beautifully. It is horse dependent as all saddles are - that said, the various panel types on saddles throughout our barn tend to work for a number of different body shapes, from the ultra-wither to the flat backed. So there are definitely options.
The saddle itself, well, I’m exceedingly thrilled with it and it’s the first saddle I have owned which I would like to change nothing about. I do bigger jumpers, as do most of the riders at my barn, and find the balance is exceptional. It puts my leg where I want it and need it and keeps it there without locking anything anywhere. It just really puts you where you need to be. I have a flat § seat with a somewhat forward flap (2.5) and the tiniest thigh block. For some time I had one without even a knee pad; the balance was no different. I really love my Butet, and although the cost was a little hard to swallow, it truly is worth every bit.
For what it’s worth I’ve ridden in or owned CWD (would be my second choice on balance alone, though did not work for Mr Withers, and not as fond of the leather), Delgrange (amazing grain leather and ideal craftsmanship as well as incredible customer svc, just too much saddle for me, and the config didn’t work for my horse), County, Antares, Schleese, Devoucoux and a zillion others. Butet definitely tops the list. I’ve just never sat in something that immediately made riding so much easier.
