where the energy requirements have been reduced (alot). If there turns out to be some hyperdimensional (ADs spacetime) possibities then the negative energy requirements would be less than Earth mass for velocity 10^2 c. The 'Inertia manipulation through metric patching' isn't a superluminal warp and its energy requirements are nil. If you couldn't read the papers because you need some way to open the pdf let me know and I'll connect you to a free download of acroread. David Waite has also been able to show that the controlling matter region is not casually separated from the ship by a event horizon.
Even though a horizon obviously exists in the matter region. It means you could turn it off from the ship.