Object AC and such? I'll admit I use it for my D&D stuff too, though largely as a reference. It's usually helpful though if you wanna figure out how hard exactly it might be to say, break down a door or something. Used to be that objects had HP equal 5 x 1 square inch in volume. This resulted in things like a common wooden door having HP in the mid one-hundreds, or a chain being broken by a a few hearty whacks with a stick.

The real issue with Object rules is if/when things are [i]equipment degrgation[/i] tries to get played, in which case shit gets crazy real fast. Realistic sure, I bet a sword will be pretty dull if I spent a whole weak cutting down a horde of goblins with it without maintenance, but it's a different kind of hassle were three fights can render a weapon into a dull club and it takes a whole hour to sharpen it to normal efficiency. But that's an extension of a rule that doesn't even exist, so take it with a grain of salt.

In short, I don't particularly mind object AC/HP as an idea. So long as Expolar doesn't try to pull a fast one like "Oh since you took some fire damage, your armor/backpack/pretty much anything you were wearing also takes damage, whoops your entire gear has been melted/destroyed in the process of you taking damage". If you're trying to sunder weapon, armor, or other items, those attacks should be made [i]specifically[/i] against those items, and otherwise don't affect your character's own health.