I realise this post is old, but I need to throw my opinion in there (you posted this on my birthday, the same day I recieved this saddle, haha). I personally like treeless saddles, but this saddle is horrible, it puts you in a bad position, and I don't care how many back raiser, wither release, air flow pads you put underneath it. Unless your horse's back is about half the width of the typical arabian, your horse will be very uncomfortable. It may flex to your horse's shape, but add your own weight and your horse will be miserable.
Here is a video of me riding Jethro in this exact saddle. Ignore my hand position, yes I realise it was horrible. The saddle made him raise his head high, and he was ignoring my ques.
The awkward chair seat that I have, that is the saddles fault. If you see my other videos, before and after this one, I have a much better position.