It requires the exact same amount of work to climb a hill with either a "fixay" or a freewheel. If your pedaling technique is actually so sloppy that you are allowing the fixed gear to rotate your legs through the rotation, then you are slowing yourself down. Where do you think the momentum thats moving your legs through the dead spot comes from? It comes 100% from you....not the fixay. Pedal correctly and (1) you will climb more efficiently, and (2) the type of drive train (FG or SS) will have absolutely no effect.