Arms & Armor Penetration

[SixStringsXD]

So I have been rather confused lately and was hoping somebody would be able to clear this up for me.

These are my current armor pen values:
55% from gear
10% from battle stance
6% from two piece t9
3.5% from food

Total = 74.5% armor pen (I have been rather unlucky with grim toll)

I heard there is going to be a nerf coming to armor pen and I was curious to know if I should even bother aiming for 100% passive armor pen or not.

The World of Warcraft Armory (http://www.wowarmory.com/character-sheet.xml?r=Mug%27thol&n=S%C3%A4%C3%A4lim%C3%A4t%C3%B6n)

[Destruyen]

with the upcoming arp nerf, you will still gem for arp until you hit the cap.

[SixStringsXD]

Ok I was thinking that myself - I recently got my hands on Iron Soul - and I have 2 Edge of Ruin and Inevitable Defeat sitting in my bank.

My next question would be - when is the right time to switch over to fury, if need be at all. I'm already doing over 5k dps so I'm pretty pleased (more in certain situations, less in fights such as Hodir, etc)

And should I still be aiming for Grim Toll/Mjornir Runestone? I know grim toll procs alot but I thought that with the nerf to armor pen they might also nerf how much it procs.

I'm just worried since I went from being 2k dps to being 5k+ dps and being a crucial part of my guild's main 10 man group (for hard modes, etc) and I really have no desire to lose that.