I didn't test this personally, but someone made a thread earlier which showed that in 40.xx, steel everything with an addy shirt is definitely better by a long way than addy everything against blunt damage.
This is because the game now considers the density of armour pieces as a buffer against blunt damage, along with their hardness... but since mail provides no blunt protection anyway, it's best to use addy for it. You never fight enemies with steel or better weaponry except in mods, so steel will still stop everything pointy, and will absorb the converted blunt damage better than addy. It's also cheaper.
Oh and greaves > leggings. Leggings are chain mail but greaves are plate, so greaves provide blunt protection.
Being speedy is good, but being fully protected is better. What my tests showed was that once you have every body part covered in a layer of chain and plate as far as possible, it's detrimental to pile on more. But go to the arena and take a unit without breastplate or greaves against one with. The breastplate and greaves unit will start winning consistently at moderate skills. Without breastplate or greaves, the upper body, lower body, and upper legs are vulnerable to blunt damage - including converted blunt damage. This is bad, because a bruised lung will put a fighter in dire straits, as will a fractured bone in their upper leg or pelvis or a fractured rib or even just severe bruising.
But if you're short on metal, it is better to give everyone that minimalist armour set than spending twice as much metal per head for the full protection.