To start I have not ridden in a saddle with a broken tree.
I have ridden a good amount on my Home Horse.
I do not think it would be that pleasant a ride even on a simulator. The HH can shift so suddenly when I get off balance that the last thing I need is my saddle “making a comment” about it.
IF I was rich I would just go straight ahead and buy around 6-8 (or would I need 10 to 20 saddles to fit all the lesson horses I ride?) saddles that fit me with different tree widths or configurations. I would not bother with adjustable tree saddles at all.
I ride the lesson horses with a Pegasus Butterfly Claudia jumping saddle. Every time I even think of maybe trying to ride in it on my HH my body starts screaming “NO, NO, NO!!!” The front of the tree in this saddle is hinged 3-ways and on a horse it took me a while to learn how to ride in it balanced. Luckily these lesson horses were extremely patient with me throughout this process, including the “rebel without a cause” sourpuss of a QH who was very definite about anything he considered abusive to him in any way (his protest was a scowl, and as the situation got worse his face got uglier and uglier, then he balked, then he started backing up for a good distance without any orders from me.) This horse’s reaction to me not being perfectly balanced in my new expensive (for me) saddle was the reason that I still ride in it years later on all the lesson horses.
I will not get up on my HH in a saddle whose tree is iffy and moving under my seat in strange ways. I do not need the irritation of the added sound effects either. I did use my Spanish Potrera saddle with a leather tree on it for a while, but that saddle is SOLID even though the front of it will eventually conform to the horse’s back. I might even feel safe if I put the EZ-fit treeless saddle on my HH, another treeless saddle that is stiff enough not to flop around on a horse’s back.
If the saddle on the HH gives you inacurate feedback about your position and movements in the saddle your body may learn habits that the horse you ride may not like at all.
Just my humble opinion of course.
Yes, I use my 50+year old saddle on my HH. This saddle is in good condition, tree and all. If I ever run into another horse that it will fit I will cheerfully ride a horse in it. I would have no problems using a 100 year old saddle on it if the saddle had a solid tree and the panels were firm, even an old fashioned English hunt seat saddle, the ones without knee rolls or much substance under my leg.
But then with my MS I have horrible balance anyway and on the HH I need something that will keep stable under my seat. There is no way to use a girth on the HH, therefor the saddle does not need billets, the saddle stays on by friction and the rider’s weight.