GH, there are 2 sorts of hoof jacks out there. More expensive with plastic base (I'd go for that one if you can), and the one I got - with flat metallic base. My farrier told me recently that those with metallic base are not very good, because they become sharp with time (I assume you have to trim a lot though before you get to that point).
I used mine when I was trimming and use now once in while when they chip and farrier is not coming in couple days. So I take a rasp and take it off myself. It IS more convenient to take flares off on jack (because rasp doesn't interfere with the knee, plus easier on back).
Just don't go for those cheap triangle ones. They are not stable and I've heard stories about the accidents with them.
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."