I don’t agree. Particularly, shielding is probabilistic, isn’t it? So the higher the flux the more shielding you need. More shielding makes it harder to accelerate, and now you’re dealing with the rocket equation again. Your target (average) speed requires a certain amount of shielding, and we may have no propulsion that can achieve that speed on any trip worth taking. Or due to the rocket equation, ever.

You're comparing an engineering decision (to use mass for shielding instead of some kind of clever redirection technique) plus another engineering decision (to use a propulsion technique subject to the rocket equation), against a direct consequence of special relativity.

General Relativity, not Special Relativity.

Special Relativity is about velocity, not bending spactime.

Special relativity is sufficient to introduce the paradoxes associated with superluminal travel.

Who is going to cleverly move all photons and .99c protons out of the way of the ship? Warping space may turn out to be the easier task.

Warp the space containing mass and energy in your travel path?

Coming up with negative energy is the hard part.

The topic of the new paper and this comment thread is primarily subliminal warp, not superluminal warp.