I have used I one. It is fine for rounding off the front or fixing chips, but is no substitute for a good trim. It may be handy if you want something in a convenient size to take to a show..it does put a nice rolled edge on the hoof, but I would sooner just take a mini size rasp instead.
I've thought aboutbuying one because I have the WORST time handling a rasp because of its size. I would love to be ableto use something like a riders rasp because of its size and grip.