I have packed a file in the past, but I just got an Accu Sharp, and plan on throwing that in my pack this year. It doesn't seem to get them (I use Zwickey Eskimos) any sharper than a file, but it is much easier to use and seems more consistent to me. (Free advice from someone who hunts and sharpens broadheads, but hasn't got a deer or elk yet with a bow-so take it for what it is worth!)
RonP