I tried the first DR option, taken from the Dawn of the Emperors box set, in my old AD&D campaigns - it worked well at high (deity) level, combined with vicious critical hit rules (18 max damage, 19 max damage & ignore armour, 20 x2 max damage & ignore armour), but at low level I don't think it works - and DR 8 for full plate is just too much, anyway. In the homegrown rules system I used for PBEM play I had armour reducing damage, but it was leather 1 pt, chain 2 pts, plate 3 pts, with weapons doing damage similar to in D&D. These figures were a bit low, but 8 is too much.
I'd suggest giving armour DR but retaining Deflection as well, maybe split between the two. So full plate currently +8 AC could be DR 4 & +4AC. Padded would be DR 1 +0AC. Traveller d20 does something similar, though further complicated by its Stamina & Lifeblood rules.
I'd suggest giving armour DR but retaining Deflection as well, maybe split between the two. So full plate currently +8 AC could be DR 4 & +4AC. Padded would be DR 1 +0AC. Traveller d20 does something similar, though further complicated by its Stamina & Lifeblood rules.