[Spaceships] balance with a) interstellar wars, b) super-science and c) size mods

[Ulzgoroth]

Originally Posted by Varyon

The fully reactionless versions have such atrocious power requirements that you cannot use a proper power plant for them - rather, you need some high-output, low-efficiency power supply.

What's the motivation for filling this niche with a short-endurance reactionless drive rather than a high-thrust reaction drive?