I would hope that any good farrier is balancing the foot regardless of discipline, though this is not always the case in practice. Lots of bad farriers out there. You won't know if he's good until you see his work, though, so I'd have her trimmed and post some pics if you're not sure what a good trim looks like. I think the fact that he trims horses in a high impact sport is a good sign, because those horses would show the effects of bad trimming faster, so he wouldn't be their farrier for too long if he was awful.
Tug on anything at all and you'll find it connected to everything else in the universe.~John Muir