Me and instructor looked into these when I didn't have a saddle but I was unimpressed. For starting a young horse they are possibly quite useful, but they do not have the support of other saddles and are just basically bareback pads.
As long as al she wants to do is plod around at a walk or slightly faster then she should be okay but they are no good for any proper work so to speak as the stirrup arrangement puts far to much pressure across a very small area of the back. If she wants a treeless saddle then she is better off with a Barefoot Cheyenne, not so expensive and far better made for neds back.
I tried one and it was the most uncomfortable thing I have ever sat on! Possibly if you have a wide flat backed horse it might be comfy but no support, but on a boney TB horrid!