By now, most of you have added inserts into your armor and have hovered over both Armor and Toughness and noticed a tooltip bug where they both say the exact same thing. Obviously since one is a percentage and one is points, they are not the exact same. I have been asked about this MANY times and have gotten an in-depth explanation of the two from one of the devs (Thanks again Chris!!). I wanted to share this info with you so you can completely understand what your inserts are helping you with and where you can improve your gear.
Armor is a multiplier. Example: if you do 50 dmg and have 50% armor reduction the net dmg is 25.
Toughness is a subtraction. Example: if you do 20 points of dmg and have 3 toughness the dmg will be 17.
The good news there is no choice between armor and toughness since you always have armor and toughness is added.
But the choice becomes interesting when you are thinking if you should add health or toughness.
Think of it this way, if you take a sniper head shot for a 120 dmg, a -3 dmg (toughness) probably isn't going to help you but an added 20 health would.
However think about things like SMG and SG…
SG fires 8 pellets -just assume 10 dmg each, -3 (toughness) off each makes them 7 but the net health savings is 24 so if you added 20 health that would help against a sniper but wouldn't save you against a shotgun but 3 toughness would.
Toughness is good against low dmg/high rof (rate of fire) and health is better against high dmg/low rof.
Then you have the other 2 factors, health regen and crit mitigation.
So even if you survive a shot, regen lets you get back into the fight faster. So it’s an interesting choice to make: health, regen or toughness.
Critical mitigation, it’s only now starting to become a real factor in the gameplay because we are seeing players getting up to proficiency level 8, maybe a 25 to 30% crit chance.
Crit mitigation inserts are designed to counter that luck factor,
Assault class health regen passive vs armor works on this theory as well
If you are constantly regening your health while in combat, very quickly you can get back 30 hp over 10 seconds. Enough to survive another bullet but that’s over time and not instant.
What’s more important depends on who you are fighting and the situation so you'll find it handy later to have multiple armors in your inventory stacked with variety of insert combinations.
On a death, this gives you a chance to change your strategy.
Hopefully this will clear up a lot of questions without creating many more! :P