I have Dales and Fell ponies. I struggled to get a treed saddle that suited me and the ponies - some are as round as they high, and very short backed, and no withers.
The treeless I prefer for myself is the genuine Trekker. I was gutted when two were stolen from our stables, and it took ages for me to scrape enough money to buy another second hand one - and it was like having an old friend back!! We also have Torsion, which my husband prefers, but I am not keen on that. I am now on the lookout for another treeless saddle. as we have not enough to go round if a few of us ride, but not sure what to go for next.
If you were closer, I would be more than happy to let you borrow the Trekker or Torsion to try.