Just makes more sense for the ranger to use oxidizer too. It gets kinda annoying hauling extra oxidizer around on the endurance with not nearly enough liquid fuel to burn it. And another thing, seems kinda OP for a generator that produces more ec output than engine input...
Edit: Also, in the movie the ranger can take off of a planet 130% the size of the earth (millers planet). Assuming the ranger's capabilities in the mod was based off of kerbin being like earth, it seems like it should have a teensy bit more liquid fuel, because when I take off of kerbin, go into a low orbit (100,000 -120,000 m) and land back onto the ground, my tank is almost empty.
I'm not asking for drastic changes, the mod is pretty great as-is. Just think these couple things would help optimize what it would be like in Interstellar.