Only that they are lovely to ride in (I used to ride a pony with one once upon a time) and they are EXPENSIVE (around £1500 I believe). I would love one for my current pony, but way out of my league I'm afraid.
I have two for sale!!! Erm I'm not advertising... They are EXCELLENT and I am not just saying that. PM me if you want to know specific stuff, but I rate them so highly.
I have had standard saddles and the air filled Flair saddles (which I did like lots until I experienced an RP)!!
I haven't (Touch wood) had any problems with my horses back since having my RP (I have always had a big obsession about saddle fit and backs). He moves better and I feel more at one with him (Strange considering how the saddle is built)!
I really think you need to check one out for yourself and make your own opinion as every saddle has it's fans and it's sceptics.
I know you can hire the RP's. Dean from Saddle Exchange is great. I found him very honest and easy to talk to. He also provides a great after sales service considering I live blooming miles away from him, I would say that was pretty good going.
You do pay a lot for the saddles, but, they don't need constant adjusting according to whether your horse is fat and unfit or slim and fit. The quality is good. Best saddle I have ever had.