Who has used one? My cinch rides up into mares elbow. Would this cinch help?

If either your saddle does not fit well, or your horse's anatomy is going to push the saddle there, then NO that cinch is NOT going to help. 

Can you post pictures of your horse with your current saddle? As well as a picture of her conformation?

I have a horse that has a very "well sprung" ribcage along with a short back. The cinch is going to ride forward no matter what I do, because of his conformation. I did try one of those cinches on him, with fleece, and when I rode him in it the first time and fleece folded over so that the hard plastic of the body of the cinch proceed to CUT INTO HIM during our ride. And the blessed soul never let on and I didn't know until we got got and I found blood on both sides. I will give kudos to the company because I did let them know what happened and they offered me to return it even though I didn't ask; I just wanted to genuinely let them know. 

So I have stuck with wool-type cinches for this horse because I never want him to get a rub!