Is Grief BiS for fury druid?

I'm currently on NM at lvl 71, and having a +358 dmg grief made p8 a cake walk. However when I put it on the damage (around 1k) was so much lower than an Insight on a colossal vogue (around 4k7). It still hits a lot harder, but I don't know how grief works. Also does it fall off a lot harder in Hell?

I have a grief, ancient's pledge, raven frost, nagel, goldwrap, Tal Rasha's helm/armor, laying of hands, mf boots and amulet.