I bought a demo Schleese Infinity II years ago from the fitter. My trainer wanted a Schleese (was pushing everyone in the barn to get one, which I later learned was so she could get her own Obrigado at a huge discount). The fitter was super and I really liked the 55-point measuring system for the horse.
The Infinity was great for my horse - the rear facing tree points gave my horse so much more shoulder freedom and the super wide gullet didn’t press on his spinal processes or dorsal ligaments, so he stayed softer in his back and his gaits became bigger, loftier, more expressive. The downside was that it was a quite heavy saddle. (There was another major downside that appeared years later but we didn’t know it at the time - read on.)
The saddle also fit my trainer well and since she was the one doing most of the riding and would be showing my horse, I opted to buy a saddle that suited her instead of me. (I did okay in it but if I had bought a saddle for me, I would probably have gotten a different model.)
Horsie did well in the Infinity for quite some years, although I had to get it refitted at least once a year as his shape was changing as he built muscle. Then it got to where it kept riding up his shoulders and I had to have it fitted every 3-4 months. The fitter - who was quite excellent - kept having to adjust the width every time because it kept opening up on its own. I finally said “that’s it” and bought a WOW that was great for my horse.
I sold the Schleese to a lady that was having a hard time finding a saddle that fit her mare but the Infinity fit super. She contacted me about six months later to report that she was also having problems with the saddle riding up her mare’s shoulders and the fitter kept having to readjust the width. It was finally determined that the composite tree had developed microcracks at the screw heads so the screws weren’t holding as well.
As mentioned, the big advantage to the Schleese was the very comprehensive measuring system, the rear-facing tree points, the extra wide gullet and a fitter that was really good. All that was outweighed by the fact that the composite tree developed tiny cracks over time at the screw heads.
So my take on them is that although they may be wonderful saddles when new, after many years of use and many adjustments/refittings, there is a risk of screw failure in the tree due to microcracks. (Bear in mind, mine was a demo so it had been around for years before I got it, and we rode my horse in it 6 days a week for 5-6 years).