umm, i would say Nidhogg is easier then Kirin for most groups, but Nidhogg will deffenitely go to town on your *** if you are not with a group who fight him regularly
the big difference is, kirin is much easier to fight as you can just pop it. Nidhogg you will have to probably camp against HNM Linkshells like TSD, Xenmetsu, Hornet, CoD, DL and so on. Nidhogg is not allways a gauranteed pop, and it is deffenitely not easy to get claim on it.
and btw, another drool body for WAR, probably better then adaberk is Ares.