Recipe for defence / damage reduction system:
Go to
http://www.sleepingimperium.rpghost.com/d20downloads.htm
Download the Grim-n-Gritty combat rules.
Ignore the hit point rules.
Use the Defence, Protection, Penetration and Called Shot rules.
Stir and cook for 2 game sessions learning time.
Eat and enjoy!
We have been using a modified version of the grim-n-gritty rules, as above, for about 2 months, and they work really well. Armour does become quite useful, but wearing armour gives you a penalty to your defence, so you end up being hit more often. We have several characters that wear no armour, and others that do, and I have noticed no appreciable difference in their survivability.
The onyl problem I have encountered is that monsters that derive a large part of their armour class from armour or natural armour become difficult to wound without massive damage weapons like greatswords. I am going to be trialing a modification in which a critical hit on a penetrate armour called shot completely ignores the armour.