Going back to your armor house rule,
Corvo, now that we (only me, you and Rocmistro apparently, since maybe Elfcrusher's Persuade roll TN seems higher than mine
) have some kind of agreement on its rationale, still I must say that something does not convince me.
First: let's consider, for example, a Dwarf with a Hauberk and a Helm. That means Damage Reduction 6, which makes him
invulnerable to all lesser enemies. Among them: Goblin archers (Damage 4, 6 on a Great or Extraordinary success), Snaga Trackers (same as Goblin), Attercops (Damage 3, 6 on a Great or Extraordinary success), Common Wolves (same as Attercops). How do you handle this?
Second: I'm totally uncomfortable with the idea of a bonus that comes into play every time a character is hit, without any kind of expenditure from him. Think about
"Rolling with the blows", AB 160 (I have the italian version, maybe the english translation and the page are not correct): you can halve the damage, but you lose your next action. Or think about
Hideous Toughness of the monsters: it's a form of Damage Reduction, but they have to spend Hate to use it.
On the other hand your house rule is free, it has drawbacks
only outside combat, and can let a character last forever, if his opponent is weak enough. This is not in the spirit of the game, where you can feel that practically all hero's resources are somehow scarce, limited and diminishing.
Third: as you can see in Elfcrusher's simulations, this rule definitely grants an advantage to armored characters, up to 20% higher win rate in comparison to unarmored ones. I guess this even enlarges applying your other Damage house rule, since unarmored characters will be totally unprotected against the tons of Damage that will come. I understand, though, that it suits very well your Arthurian's style campaign.
But, as I have a twisted tinkerer mind, all this discussing has made me develop some tweaking for your rule, that may very well keep the game balanced while providing a nice rules symmetry. Let me do some maths before, and I'll share it after your next answer