Steve,
I haven't used it before.  Let me know what you think.  I have used shag bark, shell bark, and pecan.  Pig nut has never shown up at the lumber yard here.  I have heard pig nut is more elastic in compresson, but have never had a chance to try it.  If your white hickory has that dense waxy luster where you have cut it, it can't be too bad.
I have done OK with shellbark and shagbark for flight bows.
Dan