Bob, the Federal Premium High Velocity is basically the same load as the WingShok (at least in 20 ga.), just renamed. I have shot the Wingshok out of my 20 for years. Love it. Glad I have 2 cases in back stock at home!
BTW, another difference, beside the pellets you mentioned, between the Prairie Storm and the Premium High Velocity is the PS has the Flight stopper wad. It suppose to keep a tighter pattern. I like that wad for my turkey loads, not so much for pheasant, but thats me. I also shoot an IC all season for wild birds.