[HoneyBadger]

Maybe, sometimes, but only as a side effect of being giants in the first place. If you try to rush Abyssia or Hinnom for instance, it's not likely to work out in your favor. If there's weak nations that you can stomp on, sure, you can rush them with Niefelheim, but you can also overextend yourself, and get your Nation cut out from under you, for lack of PD and the expense of your troops.

Rushing with Niefelheim is very risky, as opposed to say Helheim, where you can quickly and consistently attack your nearest neighbors, and hold on to the territory. And Niefelheim's just as vulnerable to a rush as any other nation, too, and moreso than several.