I don't see a reason for using Metalhead. Attack rating isn't an issue after investing in dex to equip a shield and the availability of attack rating from jewels/gear/charms is substantial. The helm has nice defense, otherwise the remaining affixes are less than average when compared to other options.
I used coldhunger today in Tran and Fauztinville. Its nice for Necrobots and bosses but Natha is just too good. Fhr and ias are priorities and trying to roll those affixes on double mf jewels is very time consuming. The 10% dr, along with dr from other gear makes using Idol of Scosglen a choice instead of being a mandatory pita. To top it all off, the 10% arrow proc is very strong. Thorn Strike hits a lot, and arrow carries 1/2 of our phys, added elemental damages, pierce, crushing blow and can trigger itself. It also has room for 5 additional orbs over other sus, after orbing ed%. For general gameplay, Natha is hard to beat. I'll consider adding Coldhunger to the end game section but not until I've had opportunity to use it more and in other ubers/situations.