Not sure if this is helpful...
I did check the reviews of the Rider's Rasp as I was going to buy it last spring and as mentioned by myhorsesonador, it generally doesn't get good reviews.
But in looking at this product I can easily see how it is made different and might do what you are wanting. Because of the sharp angle of the plates on the rider's rasp it really doesn't work like it advertises that it does.
I haven't used it, but have had recent issues with hooves needing touch ups between farrier visits. Just a week ago (after a lenghty discussion about hooves) my farrier showed me how to maintain the bevel on my horse's hoof with a regular rasp and guided me while I did a hoof on my horse.
While I have the strength to do manage a regular rasp, I have a bad wrist combined with small hands and I can see how this devise would be easier that using a flat rasp. But that's just my opinion
If you do decide to try it out I would love to hear back how it works. It's on my list of wanted horsie items now.