"If you're thinking in terms of wormhole and space folding exploitation, navigation and obstacle avoidance will be an overwhelming problem. Fission, fusion, and matter/anti-matter processes will likely require more mass than they produce energy to propel and still dodge the obstacles that clutter the paths between stars."

I'm not really sure of any of those technologies. However i was under the impression that both matter/antimatter annihilation propulsion and fusion propulsion would all generate far more energy than that which is necessary as fuel. Perhaps i am misinformed on that one.